* and per-CPU runqueues. Cleanups and useful suggestions
* by Davide Libenzi, preemptible kernel bits by Robert Love.
* 2003-09-03 Interactivity tuning by Con Kolivas.
+ * 2004-04-02 Scheduler domains code by Nick Piggin
*/
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/security.h>
#include <linux/notifier.h>
+#include <linux/profile.h>
#include <linux/suspend.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
+#include <linux/seq_file.h>
+#include <linux/times.h>
+#include <linux/vserver/sched.h>
+#include <linux/vs_base.h>
+#include <linux/vs_context.h>
+#include <linux/vs_cvirt.h>
+#include <asm/tlb.h>
+
+#include <asm/unistd.h>
#ifdef CONFIG_NUMA
#define cpu_to_node_mask(cpu) node_to_cpumask(cpu_to_node(cpu))
#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
-#define AVG_TIMESLICE (MIN_TIMESLICE + ((MAX_TIMESLICE - MIN_TIMESLICE) *\
- (MAX_PRIO-1-NICE_TO_PRIO(0))/(MAX_USER_PRIO - 1)))
/*
* Some helpers for converting nanosecond timing to jiffy resolution
/*
* These are the 'tuning knobs' of the scheduler:
*
- * Minimum timeslice is 10 msecs, default timeslice is 100 msecs,
- * maximum timeslice is 200 msecs. Timeslices get refilled after
- * they expire.
+ * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
+ * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
+ * Timeslices get refilled after they expire.
*/
-#define MIN_TIMESLICE ( 10 * HZ / 1000)
-#define MAX_TIMESLICE (200 * HZ / 1000)
+#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
+#define DEF_TIMESLICE (100 * HZ / 1000)
#define ON_RUNQUEUE_WEIGHT 30
#define CHILD_PENALTY 95
#define PARENT_PENALTY 100
#define PRIO_BONUS_RATIO 25
#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
#define INTERACTIVE_DELTA 2
-#define MAX_SLEEP_AVG (AVG_TIMESLICE * MAX_BONUS)
+#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
#define STARVATION_LIMIT (MAX_SLEEP_AVG)
#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
-#define NODE_THRESHOLD 125
#define CREDIT_LIMIT 100
/*
(v1) * (v2_max) / (v1_max)
#define DELTA(p) \
- (SCALE(TASK_NICE(p), 40, MAX_USER_PRIO*PRIO_BONUS_RATIO/100) + \
- INTERACTIVE_DELTA)
+ (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
#define TASK_INTERACTIVE(p) \
((p)->prio <= (p)->static_prio - DELTA(p))
((p)->prio < (rq)->curr->prio)
/*
- * BASE_TIMESLICE scales user-nice values [ -20 ... 19 ]
- * to time slice values.
+ * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
+ * to time slice values: [800ms ... 100ms ... 5ms]
*
* The higher a thread's priority, the bigger timeslices
* it gets during one round of execution. But even the lowest
* priority thread gets MIN_TIMESLICE worth of execution time.
- *
- * task_timeslice() is the interface that is used by the scheduler.
*/
-#define BASE_TIMESLICE(p) (MIN_TIMESLICE + \
- ((MAX_TIMESLICE - MIN_TIMESLICE) * \
- (MAX_PRIO-1 - (p)->static_prio) / (MAX_USER_PRIO-1)))
+#define SCALE_PRIO(x, prio) \
+ max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
-static inline unsigned int task_timeslice(task_t *p)
+static unsigned int task_timeslice(task_t *p)
{
- return BASE_TIMESLICE(p);
+ if (p->static_prio < NICE_TO_PRIO(0))
+ return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
+ else
+ return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
}
+#define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
+ < (long long) (sd)->cache_hot_time)
+
+enum idle_type
+{
+ IDLE,
+ NOT_IDLE,
+ NEWLY_IDLE,
+ MAX_IDLE_TYPES
+};
+
+struct sched_domain;
/*
* These are the runqueue data structures:
typedef struct runqueue runqueue_t;
struct prio_array {
- int nr_active;
+ unsigned int nr_active;
unsigned long bitmap[BITMAP_SIZE];
struct list_head queue[MAX_PRIO];
};
*/
struct runqueue {
spinlock_t lock;
+
+ /*
+ * nr_running and cpu_load should be in the same cacheline because
+ * remote CPUs use both these fields when doing load calculation.
+ */
+ unsigned long nr_running;
+#ifdef CONFIG_SMP
+ unsigned long cpu_load;
+#endif
unsigned long long nr_switches;
- unsigned long nr_running, expired_timestamp, nr_uninterruptible,
- timestamp_last_tick;
+ unsigned long expired_timestamp, nr_uninterruptible;
+ unsigned long long timestamp_last_tick;
task_t *curr, *idle;
struct mm_struct *prev_mm;
prio_array_t *active, *expired, arrays[2];
- int best_expired_prio, prev_cpu_load[NR_CPUS];
-#ifdef CONFIG_NUMA
- atomic_t *node_nr_running;
- int prev_node_load[MAX_NUMNODES];
-#endif
+ int best_expired_prio;
+ atomic_t nr_iowait;
+
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+
+ /* For active balancing */
+ int active_balance;
+ int push_cpu;
+
task_t *migration_thread;
struct list_head migration_queue;
+#endif
+#ifdef CONFIG_VSERVER_HARDCPU
+ struct list_head hold_queue;
+ int idle_tokens;
+#endif
- atomic_t nr_iowait;
+#ifdef CONFIG_SCHEDSTATS
+ /* latency stats */
+ struct sched_info rq_sched_info;
+
+ /* sys_sched_yield() stats */
+ unsigned long yld_exp_empty;
+ unsigned long yld_act_empty;
+ unsigned long yld_both_empty;
+ unsigned long yld_cnt;
+
+ /* schedule() stats */
+ unsigned long sched_noswitch;
+ unsigned long sched_switch;
+ unsigned long sched_cnt;
+ unsigned long sched_goidle;
+
+ /* pull_task() stats */
+ unsigned long pt_gained[MAX_IDLE_TYPES];
+ unsigned long pt_lost[MAX_IDLE_TYPES];
+
+ /* active_load_balance() stats */
+ unsigned long alb_cnt;
+ unsigned long alb_lost;
+ unsigned long alb_gained;
+ unsigned long alb_failed;
+
+ /* try_to_wake_up() stats */
+ unsigned long ttwu_cnt;
+ unsigned long ttwu_attempts;
+ unsigned long ttwu_moved;
+
+ /* wake_up_new_task() stats */
+ unsigned long wunt_cnt;
+ unsigned long wunt_moved;
+
+ /* sched_migrate_task() stats */
+ unsigned long smt_cnt;
+
+ /* sched_balance_exec() stats */
+ unsigned long sbe_cnt;
+#endif
};
static DEFINE_PER_CPU(struct runqueue, runqueues);
-#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
-#define this_rq() (&__get_cpu_var(runqueues))
-#define task_rq(p) cpu_rq(task_cpu(p))
-#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
-
-extern unsigned long __scheduling_functions_start_here;
-extern unsigned long __scheduling_functions_end_here;
-const unsigned long scheduling_functions_start_here =
- (unsigned long)&__scheduling_functions_start_here;
-const unsigned long scheduling_functions_end_here =
- (unsigned long)&__scheduling_functions_end_here;
-
/*
- * Default context-switch locking:
+ * sched-domains (multiprocessor balancing) declarations:
*/
-#ifndef prepare_arch_switch
-# define prepare_arch_switch(rq, next) do { } while (0)
-# define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock)
-# define task_running(rq, p) ((rq)->curr == (p))
-#endif
+#ifdef CONFIG_SMP
+#define SCHED_LOAD_SCALE 128UL /* increase resolution of load */
-#ifdef CONFIG_NUMA
+#define SD_BALANCE_NEWIDLE 1 /* Balance when about to become idle */
+#define SD_BALANCE_EXEC 2 /* Balance on exec */
+#define SD_WAKE_IDLE 4 /* Wake to idle CPU on task wakeup */
+#define SD_WAKE_AFFINE 8 /* Wake task to waking CPU */
+#define SD_WAKE_BALANCE 16 /* Perform balancing at task wakeup */
+#define SD_SHARE_CPUPOWER 32 /* Domain members share cpu power */
-/*
- * Keep track of running tasks.
- */
+struct sched_group {
+ struct sched_group *next; /* Must be a circular list */
+ cpumask_t cpumask;
-static atomic_t node_nr_running[MAX_NUMNODES] ____cacheline_maxaligned_in_smp =
- {[0 ...MAX_NUMNODES-1] = ATOMIC_INIT(0)};
+ /*
+ * CPU power of this group, SCHED_LOAD_SCALE being max power for a
+ * single CPU. This should be read only (except for setup). Although
+ * it will need to be written to at cpu hot(un)plug time, perhaps the
+ * cpucontrol semaphore will provide enough exclusion?
+ */
+ unsigned long cpu_power;
+};
-static inline void nr_running_init(struct runqueue *rq)
-{
- rq->node_nr_running = &node_nr_running[0];
-}
+struct sched_domain {
+ /* These fields must be setup */
+ struct sched_domain *parent; /* top domain must be null terminated */
+ struct sched_group *groups; /* the balancing groups of the domain */
+ cpumask_t span; /* span of all CPUs in this domain */
+ unsigned long min_interval; /* Minimum balance interval ms */
+ unsigned long max_interval; /* Maximum balance interval ms */
+ unsigned int busy_factor; /* less balancing by factor if busy */
+ unsigned int imbalance_pct; /* No balance until over watermark */
+ unsigned long long cache_hot_time; /* Task considered cache hot (ns) */
+ unsigned int cache_nice_tries; /* Leave cache hot tasks for # tries */
+ unsigned int per_cpu_gain; /* CPU % gained by adding domain cpus */
+ int flags; /* See SD_* */
+
+ /* Runtime fields. */
+ unsigned long last_balance; /* init to jiffies. units in jiffies */
+ unsigned int balance_interval; /* initialise to 1. units in ms. */
+ unsigned int nr_balance_failed; /* initialise to 0 */
+
+#ifdef CONFIG_SCHEDSTATS
+ /* load_balance() stats */
+ unsigned long lb_cnt[MAX_IDLE_TYPES];
+ unsigned long lb_failed[MAX_IDLE_TYPES];
+ unsigned long lb_imbalance[MAX_IDLE_TYPES];
+ unsigned long lb_nobusyg[MAX_IDLE_TYPES];
+ unsigned long lb_nobusyq[MAX_IDLE_TYPES];
+
+ /* sched_balance_exec() stats */
+ unsigned long sbe_attempts;
+ unsigned long sbe_pushed;
+
+ /* try_to_wake_up() stats */
+ unsigned long ttwu_wake_affine;
+ unsigned long ttwu_wake_balance;
+#endif
+};
-static inline void nr_running_inc(runqueue_t *rq)
-{
- atomic_inc(rq->node_nr_running);
- rq->nr_running++;
+#ifndef ARCH_HAS_SCHED_TUNE
+#ifdef CONFIG_SCHED_SMT
+#define ARCH_HAS_SCHED_WAKE_IDLE
+/* Common values for SMT siblings */
+#define SD_SIBLING_INIT (struct sched_domain) { \
+ .span = CPU_MASK_NONE, \
+ .parent = NULL, \
+ .groups = NULL, \
+ .min_interval = 1, \
+ .max_interval = 2, \
+ .busy_factor = 8, \
+ .imbalance_pct = 110, \
+ .cache_hot_time = 0, \
+ .cache_nice_tries = 0, \
+ .per_cpu_gain = 25, \
+ .flags = SD_BALANCE_NEWIDLE \
+ | SD_BALANCE_EXEC \
+ | SD_WAKE_AFFINE \
+ | SD_WAKE_IDLE \
+ | SD_SHARE_CPUPOWER, \
+ .last_balance = jiffies, \
+ .balance_interval = 1, \
+ .nr_balance_failed = 0, \
}
+#endif
-static inline void nr_running_dec(runqueue_t *rq)
-{
- atomic_dec(rq->node_nr_running);
- rq->nr_running--;
+/* Common values for CPUs */
+#define SD_CPU_INIT (struct sched_domain) { \
+ .span = CPU_MASK_NONE, \
+ .parent = NULL, \
+ .groups = NULL, \
+ .min_interval = 1, \
+ .max_interval = 4, \
+ .busy_factor = 64, \
+ .imbalance_pct = 125, \
+ .cache_hot_time = cache_decay_ticks*1000000 ? : (5*1000000/2),\
+ .cache_nice_tries = 1, \
+ .per_cpu_gain = 100, \
+ .flags = SD_BALANCE_NEWIDLE \
+ | SD_BALANCE_EXEC \
+ | SD_WAKE_AFFINE \
+ | SD_WAKE_BALANCE, \
+ .last_balance = jiffies, \
+ .balance_interval = 1, \
+ .nr_balance_failed = 0, \
}
-__init void node_nr_running_init(void)
-{
- int i;
-
- for (i = 0; i < NR_CPUS; i++) {
- if (cpu_possible(i))
- cpu_rq(i)->node_nr_running =
- &node_nr_running[cpu_to_node(i)];
- }
+/* Arch can override this macro in processor.h */
+#if defined(CONFIG_NUMA) && !defined(SD_NODE_INIT)
+#define SD_NODE_INIT (struct sched_domain) { \
+ .span = CPU_MASK_NONE, \
+ .parent = NULL, \
+ .groups = NULL, \
+ .min_interval = 8, \
+ .max_interval = 32, \
+ .busy_factor = 32, \
+ .imbalance_pct = 125, \
+ .cache_hot_time = (10*1000000), \
+ .cache_nice_tries = 1, \
+ .per_cpu_gain = 100, \
+ .flags = SD_BALANCE_EXEC \
+ | SD_WAKE_BALANCE, \
+ .last_balance = jiffies, \
+ .balance_interval = 1, \
+ .nr_balance_failed = 0, \
}
+#endif
+#endif /* ARCH_HAS_SCHED_TUNE */
+#endif
+
-#else /* !CONFIG_NUMA */
+#define for_each_domain(cpu, domain) \
+ for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
-# define nr_running_init(rq) do { } while (0)
-# define nr_running_inc(rq) do { (rq)->nr_running++; } while (0)
-# define nr_running_dec(rq) do { (rq)->nr_running--; } while (0)
+#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
+#define this_rq() (&__get_cpu_var(runqueues))
+#define task_rq(p) cpu_rq(task_cpu(p))
+#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
-#endif /* CONFIG_NUMA */
+/*
+ * Default context-switch locking:
+ */
+#ifndef prepare_arch_switch
+# define prepare_arch_switch(rq, next) do { } while (0)
+# define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock)
+# define task_running(rq, p) ((rq)->curr == (p))
+#endif
/*
* task_rq_lock - lock the runqueue a given task resides on and disable
* interrupts. Note the ordering: we can safely lookup the task_rq without
* explicitly disabling preemption.
*/
-static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
+static runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
{
struct runqueue *rq;
spin_unlock_irqrestore(&rq->lock, *flags);
}
+#ifdef CONFIG_SCHEDSTATS
+/*
+ * bump this up when changing the output format or the meaning of an existing
+ * format, so that tools can adapt (or abort)
+ */
+#define SCHEDSTAT_VERSION 10
+
+static int show_schedstat(struct seq_file *seq, void *v)
+{
+ int cpu;
+ enum idle_type itype;
+
+ seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
+ seq_printf(seq, "timestamp %lu\n", jiffies);
+ for_each_online_cpu(cpu) {
+ runqueue_t *rq = cpu_rq(cpu);
+#ifdef CONFIG_SMP
+ struct sched_domain *sd;
+ int dcnt = 0;
+#endif
+
+ /* runqueue-specific stats */
+ seq_printf(seq,
+ "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu "
+ "%lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
+ cpu, rq->yld_both_empty,
+ rq->yld_act_empty, rq->yld_exp_empty,
+ rq->yld_cnt, rq->sched_noswitch,
+ rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
+ rq->alb_cnt, rq->alb_gained, rq->alb_lost,
+ rq->alb_failed,
+ rq->ttwu_cnt, rq->ttwu_moved, rq->ttwu_attempts,
+ rq->wunt_cnt, rq->wunt_moved,
+ rq->smt_cnt, rq->sbe_cnt, rq->rq_sched_info.cpu_time,
+ rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
+
+ for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++)
+ seq_printf(seq, " %lu %lu", rq->pt_gained[itype],
+ rq->pt_lost[itype]);
+ seq_printf(seq, "\n");
+
+#ifdef CONFIG_SMP
+ /* domain-specific stats */
+ for_each_domain(cpu, sd) {
+ char mask_str[NR_CPUS];
+
+ cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
+ seq_printf(seq, "domain%d %s", dcnt++, mask_str);
+ for (itype = IDLE; itype < MAX_IDLE_TYPES; itype++) {
+ seq_printf(seq, " %lu %lu %lu %lu %lu",
+ sd->lb_cnt[itype],
+ sd->lb_failed[itype],
+ sd->lb_imbalance[itype],
+ sd->lb_nobusyq[itype],
+ sd->lb_nobusyg[itype]);
+ }
+ seq_printf(seq, " %lu %lu %lu %lu\n",
+ sd->sbe_pushed, sd->sbe_attempts,
+ sd->ttwu_wake_affine, sd->ttwu_wake_balance);
+ }
+#endif
+ }
+ return 0;
+}
+
+static int schedstat_open(struct inode *inode, struct file *file)
+{
+ unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
+ char *buf = kmalloc(size, GFP_KERNEL);
+ struct seq_file *m;
+ int res;
+
+ if (!buf)
+ return -ENOMEM;
+ res = single_open(file, show_schedstat, NULL);
+ if (!res) {
+ m = file->private_data;
+ m->buf = buf;
+ m->size = size;
+ } else
+ kfree(buf);
+ return res;
+}
+
+struct file_operations proc_schedstat_operations = {
+ .open = schedstat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+# define schedstat_inc(rq, field) rq->field++;
+# define schedstat_add(rq, field, amt) rq->field += amt;
+#else /* !CONFIG_SCHEDSTATS */
+# define schedstat_inc(rq, field) do { } while (0);
+# define schedstat_add(rq, field, amt) do { } while (0);
+#endif
+
/*
* rq_lock - lock a given runqueue and disable interrupts.
*/
-static inline runqueue_t *this_rq_lock(void)
+static runqueue_t *this_rq_lock(void)
{
runqueue_t *rq;
spin_unlock_irq(&rq->lock);
}
+#ifdef CONFIG_SCHEDSTATS
+/*
+ * Called when a process is dequeued from the active array and given
+ * the cpu. We should note that with the exception of interactive
+ * tasks, the expired queue will become the active queue after the active
+ * queue is empty, without explicitly dequeuing and requeuing tasks in the
+ * expired queue. (Interactive tasks may be requeued directly to the
+ * active queue, thus delaying tasks in the expired queue from running;
+ * see scheduler_tick()).
+ *
+ * This function is only called from sched_info_arrive(), rather than
+ * dequeue_task(). Even though a task may be queued and dequeued multiple
+ * times as it is shuffled about, we're really interested in knowing how
+ * long it was from the *first* time it was queued to the time that it
+ * finally hit a cpu.
+ */
+static inline void sched_info_dequeued(task_t *t)
+{
+ t->sched_info.last_queued = 0;
+}
+
+/*
+ * Called when a task finally hits the cpu. We can now calculate how
+ * long it was waiting to run. We also note when it began so that we
+ * can keep stats on how long its timeslice is.
+ */
+static inline void sched_info_arrive(task_t *t)
+{
+ unsigned long now = jiffies, diff = 0;
+ struct runqueue *rq = task_rq(t);
+
+ if (t->sched_info.last_queued)
+ diff = now - t->sched_info.last_queued;
+ sched_info_dequeued(t);
+ t->sched_info.run_delay += diff;
+ t->sched_info.last_arrival = now;
+ t->sched_info.pcnt++;
+
+ if (!rq)
+ return;
+
+ rq->rq_sched_info.run_delay += diff;
+ rq->rq_sched_info.pcnt++;
+}
+
+/*
+ * Called when a process is queued into either the active or expired
+ * array. The time is noted and later used to determine how long we
+ * had to wait for us to reach the cpu. Since the expired queue will
+ * become the active queue after active queue is empty, without dequeuing
+ * and requeuing any tasks, we are interested in queuing to either. It
+ * is unusual but not impossible for tasks to be dequeued and immediately
+ * requeued in the same or another array: this can happen in sched_yield(),
+ * set_user_nice(), and even load_balance() as it moves tasks from runqueue
+ * to runqueue.
+ *
+ * This function is only called from enqueue_task(), but also only updates
+ * the timestamp if it is already not set. It's assumed that
+ * sched_info_dequeued() will clear that stamp when appropriate.
+ */
+static inline void sched_info_queued(task_t *t)
+{
+ if (!t->sched_info.last_queued)
+ t->sched_info.last_queued = jiffies;
+}
+
+/*
+ * Called when a process ceases being the active-running process, either
+ * voluntarily or involuntarily. Now we can calculate how long we ran.
+ */
+static inline void sched_info_depart(task_t *t)
+{
+ struct runqueue *rq = task_rq(t);
+ unsigned long diff = jiffies - t->sched_info.last_arrival;
+
+ t->sched_info.cpu_time += diff;
+
+ if (rq)
+ rq->rq_sched_info.cpu_time += diff;
+}
+
+/*
+ * Called when tasks are switched involuntarily due, typically, to expiring
+ * their time slice. (This may also be called when switching to or from
+ * the idle task.) We are only called when prev != next.
+ */
+static inline void sched_info_switch(task_t *prev, task_t *next)
+{
+ struct runqueue *rq = task_rq(prev);
+
+ /*
+ * prev now departs the cpu. It's not interesting to record
+ * stats about how efficient we were at scheduling the idle
+ * process, however.
+ */
+ if (prev != rq->idle)
+ sched_info_depart(prev);
+
+ if (next != rq->idle)
+ sched_info_arrive(next);
+}
+#else
+#define sched_info_queued(t) do { } while (0)
+#define sched_info_switch(t, next) do { } while (0)
+#endif /* CONFIG_SCHEDSTATS */
+
/*
* Adding/removing a task to/from a priority array:
*/
-static inline void dequeue_task(struct task_struct *p, prio_array_t *array)
+static void dequeue_task(struct task_struct *p, prio_array_t *array)
{
array->nr_active--;
list_del(&p->run_list);
__clear_bit(p->prio, array->bitmap);
}
-static inline void enqueue_task(struct task_struct *p, prio_array_t *array)
+static void enqueue_task(struct task_struct *p, prio_array_t *array)
{
+ sched_info_queued(p);
list_add_tail(&p->run_list, array->queue + p->prio);
__set_bit(p->prio, array->bitmap);
array->nr_active++;
p->array = array;
}
+/*
+ * Used by the migration code - we pull tasks from the head of the
+ * remote queue so we want these tasks to show up at the head of the
+ * local queue:
+ */
+static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
+{
+ list_add(&p->run_list, array->queue + p->prio);
+ __set_bit(p->prio, array->bitmap);
+ array->nr_active++;
+ p->array = array;
+}
+
/*
* effective_prio - return the priority that is based on the static
* priority but is modified by bonuses/penalties.
bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
prio = p->static_prio - bonus;
+ if (task_vx_flags(p, VXF_SCHED_PRIO, 0))
+ prio += effective_vavavoom(p, MAX_USER_PRIO);
+
if (prio < MAX_RT_PRIO)
prio = MAX_RT_PRIO;
if (prio > MAX_PRIO-1)
static inline void __activate_task(task_t *p, runqueue_t *rq)
{
enqueue_task(p, rq->active);
- nr_running_inc(rq);
+ rq->nr_running++;
+}
+
+/*
+ * __activate_idle_task - move idle task to the _front_ of runqueue.
+ */
+static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
+{
+ enqueue_task_head(p, rq->active);
+ rq->nr_running++;
}
static void recalc_task_prio(task_t *p, unsigned long long now)
if (p->mm && p->activated != -1 &&
sleep_time > INTERACTIVE_SLEEP(p)) {
p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
- AVG_TIMESLICE);
+ DEF_TIMESLICE);
if (!HIGH_CREDIT(p))
p->interactive_credit++;
} else {
* Update all the scheduling statistics stuff. (sleep average
* calculation, priority modifiers, etc.)
*/
-static inline void activate_task(task_t *p, runqueue_t *rq)
+static void activate_task(task_t *p, runqueue_t *rq, int local)
{
- unsigned long long now = sched_clock();
+ unsigned long long now;
+
+ now = sched_clock();
+#ifdef CONFIG_SMP
+ if (!local) {
+ /* Compensate for drifting sched_clock */
+ runqueue_t *this_rq = this_rq();
+ now = (now - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
+ }
+#endif
recalc_task_prio(p, now);
}
p->timestamp = now;
+ vx_activate_task(p);
__activate_task(p, rq);
}
/*
* deactivate_task - remove a task from the runqueue.
*/
-static inline void deactivate_task(struct task_struct *p, runqueue_t *rq)
+static void __deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- nr_running_dec(rq);
+ rq->nr_running--;
if (p->state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible++;
dequeue_task(p, p->array);
+
p->array = NULL;
}
+static void deactivate_task(struct task_struct *p, runqueue_t *rq)
+{
+ __deactivate_task(p, rq);
+ vx_deactivate_task(p);
+}
+
/*
* resched_task - mark a task 'to be rescheduled now'.
*
* might also involve a cross-CPU call to trigger the scheduler on
* the target CPU.
*/
-static inline void resched_task(task_t *p)
-{
#ifdef CONFIG_SMP
+static void resched_task(task_t *p)
+{
int need_resched, nrpolling;
- preempt_disable();
+ BUG_ON(!spin_is_locked(&task_rq(p)->lock));
+
/* minimise the chance of sending an interrupt to poll_idle() */
nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
smp_send_reschedule(task_cpu(p));
- preempt_enable();
+}
#else
+static inline void resched_task(task_t *p)
+{
set_tsk_need_resched(p);
-#endif
}
+#endif
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
*/
-inline int task_curr(task_t *p)
+inline int task_curr(const task_t *p)
{
return cpu_curr(task_cpu(p)) == p;
}
#ifdef CONFIG_SMP
+enum request_type {
+ REQ_MOVE_TASK,
+ REQ_SET_DOMAIN,
+};
+
typedef struct {
struct list_head list;
+ enum request_type type;
+
+ /* For REQ_MOVE_TASK */
task_t *task;
+ int dest_cpu;
+
+ /* For REQ_SET_DOMAIN */
+ struct sched_domain *sd;
+
struct completion done;
} migration_req_t;
/*
- * The task's runqueue lock must be held, and the new mask must be valid.
+ * The task's runqueue lock must be held.
* Returns true if you have to wait for migration thread.
*/
-static int __set_cpus_allowed(task_t *p, cpumask_t new_mask,
- migration_req_t *req)
+static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
{
runqueue_t *rq = task_rq(p);
- p->cpus_allowed = new_mask;
- /*
- * Can the task run on the task's current CPU? If not then
- * migrate the thread off to a proper CPU.
- */
- if (cpu_isset(task_cpu(p), new_mask))
- return 0;
-
/*
* If the task is not on a runqueue (and not running), then
* it is sufficient to simply update the task's cpu field.
*/
if (!p->array && !task_running(rq, p)) {
- set_task_cpu(p, any_online_cpu(p->cpus_allowed));
+ set_task_cpu(p, dest_cpu);
return 0;
}
init_completion(&req->done);
+ req->type = REQ_MOVE_TASK;
req->task = p;
+ req->dest_cpu = dest_cpu;
list_add(&req->list, &rq->migration_queue);
return 1;
}
EXPORT_SYMBOL_GPL(kick_process);
+/*
+ * Return a low guess at the load of a migration-source cpu.
+ *
+ * We want to under-estimate the load of migration sources, to
+ * balance conservatively.
+ */
+static inline unsigned long source_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return min(rq->cpu_load, load_now);
+}
+
+/*
+ * Return a high guess at the load of a migration-target cpu
+ */
+static inline unsigned long target_load(int cpu)
+{
+ runqueue_t *rq = cpu_rq(cpu);
+ unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
+
+ return max(rq->cpu_load, load_now);
+}
+
+#endif
+
+/*
+ * wake_idle() is useful especially on SMT architectures to wake a
+ * task onto an idle sibling if we would otherwise wake it onto a
+ * busy sibling.
+ *
+ * Returns the CPU we should wake onto.
+ */
+#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
+static int wake_idle(int cpu, task_t *p)
+{
+ cpumask_t tmp;
+ runqueue_t *rq = cpu_rq(cpu);
+ struct sched_domain *sd;
+ int i;
+
+ if (idle_cpu(cpu))
+ return cpu;
+
+ sd = rq->sd;
+ if (!(sd->flags & SD_WAKE_IDLE))
+ return cpu;
+
+ cpus_and(tmp, sd->span, cpu_online_map);
+ cpus_and(tmp, tmp, p->cpus_allowed);
+
+ for_each_cpu_mask(i, tmp) {
+ if (idle_cpu(i))
+ return i;
+ }
+
+ return cpu;
+}
+#else
+static inline int wake_idle(int cpu, task_t *p)
+{
+ return cpu;
+}
#endif
/***
*/
static int try_to_wake_up(task_t * p, unsigned int state, int sync)
{
+ int cpu, this_cpu, success = 0;
unsigned long flags;
- int success = 0;
long old_state;
runqueue_t *rq;
+#ifdef CONFIG_SMP
+ unsigned long load, this_load;
+ struct sched_domain *sd;
+ int new_cpu;
+#endif
-repeat_lock_task:
rq = task_rq_lock(p, &flags);
+ schedstat_inc(rq, ttwu_cnt);
old_state = p->state;
- if (old_state & state) {
- if (!p->array) {
+ if (!(old_state & state))
+ goto out;
+
+ if (p->array)
+ goto out_running;
+
+ cpu = task_cpu(p);
+ this_cpu = smp_processor_id();
+
+#ifdef CONFIG_SMP
+ if (unlikely(task_running(rq, p)))
+ goto out_activate;
+
+ new_cpu = cpu;
+
+ if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
+ goto out_set_cpu;
+
+ load = source_load(cpu);
+ this_load = target_load(this_cpu);
+
+ /*
+ * If sync wakeup then subtract the (maximum possible) effect of
+ * the currently running task from the load of the current CPU:
+ */
+ if (sync)
+ this_load -= SCHED_LOAD_SCALE;
+
+ /* Don't pull the task off an idle CPU to a busy one */
+ if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
+ goto out_set_cpu;
+
+ new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+ /*
+ * Scan domains for affine wakeup and passive balancing
+ * possibilities.
+ */
+ for_each_domain(this_cpu, sd) {
+ unsigned int imbalance;
+ /*
+ * Start passive balancing when half the imbalance_pct
+ * limit is reached.
+ */
+ imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
+
+ if ((sd->flags & SD_WAKE_AFFINE) &&
+ !task_hot(p, rq->timestamp_last_tick, sd)) {
/*
- * Fast-migrate the task if it's not running or runnable
- * currently. Do not violate hard affinity.
+ * This domain has SD_WAKE_AFFINE and p is cache cold
+ * in this domain.
*/
- if (unlikely(sync && !task_running(rq, p) &&
- (task_cpu(p) != smp_processor_id()) &&
- cpu_isset(smp_processor_id(),
- p->cpus_allowed) &&
- !cpu_is_offline(smp_processor_id()))) {
- set_task_cpu(p, smp_processor_id());
- task_rq_unlock(rq, &flags);
- goto repeat_lock_task;
- }
- if (old_state == TASK_UNINTERRUPTIBLE) {
- rq->nr_uninterruptible--;
- /*
- * Tasks on involuntary sleep don't earn
- * sleep_avg beyond just interactive state.
- */
- p->activated = -1;
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_affine);
+ goto out_set_cpu;
}
- if (sync && (task_cpu(p) == smp_processor_id()))
- __activate_task(p, rq);
- else {
- activate_task(p, rq);
- if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
+ } else if ((sd->flags & SD_WAKE_BALANCE) &&
+ imbalance*this_load <= 100*load) {
+ /*
+ * This domain has SD_WAKE_BALANCE and there is
+ * an imbalance.
+ */
+ if (cpu_isset(cpu, sd->span)) {
+ schedstat_inc(sd, ttwu_wake_balance);
+ goto out_set_cpu;
}
- success = 1;
}
- p->state = TASK_RUNNING;
}
- task_rq_unlock(rq, &flags);
-
- return success;
-}
-int fastcall wake_up_process(task_t * p)
-{
- return try_to_wake_up(p, TASK_STOPPED |
- TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
-}
-EXPORT_SYMBOL(wake_up_process);
+ new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
+out_set_cpu:
+ schedstat_inc(rq, ttwu_attempts);
+ new_cpu = wake_idle(new_cpu, p);
+ if (new_cpu != cpu && cpu_isset(new_cpu, p->cpus_allowed)) {
+ schedstat_inc(rq, ttwu_moved);
+ set_task_cpu(p, new_cpu);
+ task_rq_unlock(rq, &flags);
+ /* might preempt at this point */
+ rq = task_rq_lock(p, &flags);
+ old_state = p->state;
+ if (!(old_state & state))
+ goto out;
+ if (p->array)
+ goto out_running;
+
+ this_cpu = smp_processor_id();
+ cpu = task_cpu(p);
+ }
+
+out_activate:
+#endif /* CONFIG_SMP */
+ if (old_state == TASK_UNINTERRUPTIBLE) {
+ rq->nr_uninterruptible--;
+ /*
+ * Tasks on involuntary sleep don't earn
+ * sleep_avg beyond just interactive state.
+ */
+ p->activated = -1;
+ }
+
+ /*
+ * Sync wakeups (i.e. those types of wakeups where the waker
+ * has indicated that it will leave the CPU in short order)
+ * don't trigger a preemption, if the woken up task will run on
+ * this cpu. (in this case the 'I will reschedule' promise of
+ * the waker guarantees that the freshly woken up task is going
+ * to be considered on this CPU.)
+ */
+ activate_task(p, rq, cpu == this_cpu);
+ if (!sync || cpu != this_cpu) {
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+ }
+ success = 1;
+
+out_running:
+ p->state = TASK_RUNNING;
+out:
+ task_rq_unlock(rq, &flags);
+
+ return success;
+}
+
+int fastcall wake_up_process(task_t * p)
+{
+ return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
+ TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
+}
+
+EXPORT_SYMBOL(wake_up_process);
int fastcall wake_up_state(task_t *p, unsigned int state)
{
return try_to_wake_up(p, state, 0);
}
+#ifdef CONFIG_SMP
+static int find_idlest_cpu(struct task_struct *p, int this_cpu,
+ struct sched_domain *sd);
+#endif
+
/*
* Perform scheduler related setup for a newly forked process p.
* p is forked by current.
INIT_LIST_HEAD(&p->run_list);
p->array = NULL;
spin_lock_init(&p->switch_lock);
+#ifdef CONFIG_SCHEDSTATS
+ memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif
#ifdef CONFIG_PREEMPT
/*
* During context-switch we hold precisely one spinlock, which
p->first_time_slice = 1;
current->time_slice >>= 1;
p->timestamp = sched_clock();
- if (!current->time_slice) {
+ if (unlikely(!current->time_slice)) {
/*
- * This case is rare, it happens when the parent has only
- * a single jiffy left from its timeslice. Taking the
+ * This case is rare, it happens when the parent has only
+ * a single jiffy left from its timeslice. Taking the
* runqueue lock is not a problem.
*/
current->time_slice = 1;
}
/*
- * wake_up_forked_process - wake up a freshly forked process.
+ * wake_up_new_task - wake up a newly created task for the first time.
*
* This function will do some initial scheduler statistics housekeeping
- * that must be done for every newly created process.
+ * that must be done for every newly created context, then puts the task
+ * on the runqueue and wakes it.
*/
-void fastcall wake_up_forked_process(task_t * p)
+void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
{
unsigned long flags;
- runqueue_t *rq = task_rq_lock(current, &flags);
+ int this_cpu, cpu;
+ runqueue_t *rq, *this_rq;
+
+ rq = task_rq_lock(p, &flags);
+ cpu = task_cpu(p);
+ this_cpu = smp_processor_id();
BUG_ON(p->state != TASK_RUNNING);
+ schedstat_inc(rq, wunt_cnt);
/*
* We decrease the sleep average of forking parents
* and children as well, to keep max-interactive tasks
- * from forking tasks that are max-interactive.
+ * from forking tasks that are max-interactive. The parent
+ * (current) is done further down, under its lock.
*/
- current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
- PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
-
p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
p->interactive_credit = 0;
p->prio = effective_prio(p);
- set_task_cpu(p, smp_processor_id());
- if (unlikely(!current->array))
+ vx_activate_task(p);
+ if (likely(cpu == this_cpu)) {
+ if (!(clone_flags & CLONE_VM)) {
+ /*
+ * The VM isn't cloned, so we're in a good position to
+ * do child-runs-first in anticipation of an exec. This
+ * usually avoids a lot of COW overhead.
+ */
+ if (unlikely(!current->array))
+ __activate_task(p, rq);
+ else {
+ p->prio = current->prio;
+ list_add_tail(&p->run_list, ¤t->run_list);
+ p->array = current->array;
+ p->array->nr_active++;
+ rq->nr_running++;
+ }
+ set_need_resched();
+ } else
+ /* Run child last */
+ __activate_task(p, rq);
+ /*
+ * We skip the following code due to cpu == this_cpu
+ *
+ * task_rq_unlock(rq, &flags);
+ * this_rq = task_rq_lock(current, &flags);
+ */
+ this_rq = rq;
+ } else {
+ this_rq = cpu_rq(this_cpu);
+
+ /*
+ * Not the local CPU - must adjust timestamp. This should
+ * get optimised away in the !CONFIG_SMP case.
+ */
+ p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
+ + rq->timestamp_last_tick;
__activate_task(p, rq);
- else {
- p->prio = current->prio;
- list_add_tail(&p->run_list, ¤t->run_list);
- p->array = current->array;
- p->array->nr_active++;
- nr_running_inc(rq);
+ if (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+
+ schedstat_inc(rq, wunt_moved);
+ /*
+ * Parent and child are on different CPUs, now get the
+ * parent runqueue to update the parent's ->sleep_avg:
+ */
+ task_rq_unlock(rq, &flags);
+ this_rq = task_rq_lock(current, &flags);
}
- task_rq_unlock(rq, &flags);
+ current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
+ PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
+ task_rq_unlock(this_rq, &flags);
}
/*
unsigned long flags;
runqueue_t *rq;
- local_irq_save(flags);
- if (p->first_time_slice) {
- p->parent->time_slice += p->time_slice;
- if (unlikely(p->parent->time_slice > MAX_TIMESLICE))
- p->parent->time_slice = MAX_TIMESLICE;
- }
- local_irq_restore(flags);
/*
* If the child was a (relative-) CPU hog then decrease
* the sleep_avg of the parent as well.
*/
rq = task_rq_lock(p->parent, &flags);
+ if (p->first_time_slice) {
+ p->parent->time_slice += p->time_slice;
+ if (unlikely(p->parent->time_slice > task_timeslice(p)))
+ p->parent->time_slice = task_timeslice(p);
+ }
if (p->sleep_avg < p->parent->sleep_avg)
p->parent->sleep_avg = p->parent->sleep_avg /
(EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
* with the lock held can cause deadlocks; see schedule() for
* details.)
*/
-static inline void finish_task_switch(task_t *prev)
+static void finish_task_switch(task_t *prev)
{
runqueue_t *rq = this_rq();
struct mm_struct *mm = rq->prev_mm;
* still held, otherwise prev could be scheduled on another cpu, die
* there before we look at prev->state, and then the reference would
* be dropped twice.
- * Manfred Spraul <manfred@colorfullife.com>
+ * Manfred Spraul <manfred@colorfullife.com>
*/
prev_task_flags = prev->flags;
finish_arch_switch(rq, prev);
{
unsigned long i, sum = 0;
- for (i = 0; i < NR_CPUS; i++)
+ for_each_online_cpu(i)
sum += cpu_rq(i)->nr_running;
return sum;
return sum;
}
+#ifdef CONFIG_SMP
+
/*
* double_rq_lock - safely lock two runqueues
*
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
-static inline void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
+static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
{
if (rq1 == rq2)
spin_lock(&rq1->lock);
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
-static inline void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
+static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
{
spin_unlock(&rq1->lock);
if (rq1 != rq2)
spin_unlock(&rq2->lock);
}
-#ifdef CONFIG_NUMA
/*
- * If dest_cpu is allowed for this process, migrate the task to it.
- * This is accomplished by forcing the cpu_allowed mask to only
- * allow dest_cpu, which will force the cpu onto dest_cpu. Then
- * the cpu_allowed mask is restored.
+ * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
*/
-static void sched_migrate_task(task_t *p, int dest_cpu)
+static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
{
- runqueue_t *rq;
- migration_req_t req;
- unsigned long flags;
- cpumask_t old_mask, new_mask = cpumask_of_cpu(dest_cpu);
-
- lock_cpu_hotplug();
- rq = task_rq_lock(p, &flags);
- old_mask = p->cpus_allowed;
- if (!cpu_isset(dest_cpu, old_mask) || !cpu_online(dest_cpu))
- goto out;
-
- /* force the process onto the specified CPU */
- if (__set_cpus_allowed(p, new_mask, &req)) {
- /* Need to wait for migration thread. */
- task_rq_unlock(rq, &flags);
- wake_up_process(rq->migration_thread);
- wait_for_completion(&req.done);
-
- /* If we raced with sys_sched_setaffinity, don't
- * restore mask. */
- rq = task_rq_lock(p, &flags);
- if (likely(cpus_equal(p->cpus_allowed, new_mask))) {
- /* Restore old mask: won't need migration
- * thread, since current cpu is allowed. */
- BUG_ON(__set_cpus_allowed(p, old_mask, NULL));
- }
+ if (unlikely(!spin_trylock(&busiest->lock))) {
+ if (busiest < this_rq) {
+ spin_unlock(&this_rq->lock);
+ spin_lock(&busiest->lock);
+ spin_lock(&this_rq->lock);
+ } else
+ spin_lock(&busiest->lock);
}
-out:
- task_rq_unlock(rq, &flags);
- unlock_cpu_hotplug();
}
/*
- * Find the least loaded CPU. Slightly favor the current CPU by
- * setting its runqueue length as the minimum to start.
+ * find_idlest_cpu - find the least busy runqueue.
*/
-static int sched_best_cpu(struct task_struct *p)
+static int find_idlest_cpu(struct task_struct *p, int this_cpu,
+ struct sched_domain *sd)
{
- int i, minload, load, best_cpu, node = 0;
- cpumask_t cpumask;
+ unsigned long load, min_load, this_load;
+ int i, min_cpu;
+ cpumask_t mask;
- best_cpu = task_cpu(p);
- if (cpu_rq(best_cpu)->nr_running <= 2)
- return best_cpu;
+ min_cpu = UINT_MAX;
+ min_load = ULONG_MAX;
- minload = 10000000;
- for_each_node_with_cpus(i) {
- /*
- * Node load is always divided by nr_cpus_node to normalise
- * load values in case cpu count differs from node to node.
- * We first multiply node_nr_running by 10 to get a little
- * better resolution.
- */
- load = 10 * atomic_read(&node_nr_running[i]) / nr_cpus_node(i);
- if (load < minload) {
- minload = load;
- node = i;
- }
- }
+ cpus_and(mask, sd->span, cpu_online_map);
+ cpus_and(mask, mask, p->cpus_allowed);
- minload = 10000000;
- cpumask = node_to_cpumask(node);
- for (i = 0; i < NR_CPUS; ++i) {
- if (!cpu_isset(i, cpumask))
- continue;
- if (cpu_rq(i)->nr_running < minload) {
- best_cpu = i;
- minload = cpu_rq(i)->nr_running;
+ for_each_cpu_mask(i, mask) {
+ load = target_load(i);
+
+ if (load < min_load) {
+ min_cpu = i;
+ min_load = load;
+
+ /* break out early on an idle CPU: */
+ if (!min_load)
+ break;
}
}
- return best_cpu;
-}
-void sched_balance_exec(void)
-{
- int new_cpu;
+ /* add +1 to account for the new task */
+ this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
- if (numnodes > 1) {
- new_cpu = sched_best_cpu(current);
- if (new_cpu != smp_processor_id())
- sched_migrate_task(current, new_cpu);
- }
+ /*
+ * Would with the addition of the new task to the
+ * current CPU there be an imbalance between this
+ * CPU and the idlest CPU?
+ *
+ * Use half of the balancing threshold - new-context is
+ * a good opportunity to balance.
+ */
+ if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100)
+ return min_cpu;
+
+ return this_cpu;
}
/*
- * Find the busiest node. All previous node loads contribute with a
- * geometrically deccaying weight to the load measure:
- * load_{t} = load_{t-1}/2 + nr_node_running_{t}
- * This way sudden load peaks are flattened out a bit.
- * Node load is divided by nr_cpus_node() in order to compare nodes
- * of different cpu count but also [first] multiplied by 10 to
- * provide better resolution.
+ * If dest_cpu is allowed for this process, migrate the task to it.
+ * This is accomplished by forcing the cpu_allowed mask to only
+ * allow dest_cpu, which will force the cpu onto dest_cpu. Then
+ * the cpu_allowed mask is restored.
*/
-static int find_busiest_node(int this_node)
+static void sched_migrate_task(task_t *p, int dest_cpu)
{
- int i, node = -1, load, this_load, maxload;
-
- if (!nr_cpus_node(this_node))
- return node;
- this_load = maxload = (this_rq()->prev_node_load[this_node] >> 1)
- + (10 * atomic_read(&node_nr_running[this_node])
- / nr_cpus_node(this_node));
- this_rq()->prev_node_load[this_node] = this_load;
- for_each_node_with_cpus(i) {
- if (i == this_node)
- continue;
- load = (this_rq()->prev_node_load[i] >> 1)
- + (10 * atomic_read(&node_nr_running[i])
- / nr_cpus_node(i));
- this_rq()->prev_node_load[i] = load;
- if (load > maxload && (100*load > NODE_THRESHOLD*this_load)) {
- maxload = load;
- node = i;
- }
- }
- return node;
-}
-
-#endif /* CONFIG_NUMA */
+ migration_req_t req;
+ runqueue_t *rq;
+ unsigned long flags;
-#ifdef CONFIG_SMP
+ rq = task_rq_lock(p, &flags);
+ if (!cpu_isset(dest_cpu, p->cpus_allowed)
+ || unlikely(cpu_is_offline(dest_cpu)))
+ goto out;
-/*
- * double_lock_balance - lock the busiest runqueue
- *
- * this_rq is locked already. Recalculate nr_running if we have to
- * drop the runqueue lock.
- */
-static inline
-unsigned int double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest,
- int this_cpu, int idle,
- unsigned int nr_running)
-{
- if (unlikely(!spin_trylock(&busiest->lock))) {
- if (busiest < this_rq) {
- spin_unlock(&this_rq->lock);
- spin_lock(&busiest->lock);
- spin_lock(&this_rq->lock);
- /* Need to recalculate nr_running */
- if (idle || (this_rq->nr_running >
- this_rq->prev_cpu_load[this_cpu]))
- nr_running = this_rq->nr_running;
- else
- nr_running = this_rq->prev_cpu_load[this_cpu];
- } else
- spin_lock(&busiest->lock);
+ schedstat_inc(rq, smt_cnt);
+ /* force the process onto the specified CPU */
+ if (migrate_task(p, dest_cpu, &req)) {
+ /* Need to wait for migration thread (might exit: take ref). */
+ struct task_struct *mt = rq->migration_thread;
+ get_task_struct(mt);
+ task_rq_unlock(rq, &flags);
+ wake_up_process(mt);
+ put_task_struct(mt);
+ wait_for_completion(&req.done);
+ return;
}
- return nr_running;
+out:
+ task_rq_unlock(rq, &flags);
}
/*
- * find_busiest_queue - find the busiest runqueue among the cpus in cpumask.
+ * sched_exec(): find the highest-level, exec-balance-capable
+ * domain and try to migrate the task to the least loaded CPU.
+ *
+ * execve() is a valuable balancing opportunity, because at this point
+ * the task has the smallest effective memory and cache footprint.
*/
-static inline
-runqueue_t *find_busiest_queue(runqueue_t *this_rq, int this_cpu, int idle,
- int *imbalance, cpumask_t cpumask)
+void sched_exec(void)
{
- int nr_running, load, max_load, i;
- runqueue_t *busiest, *rq_src;
-
- /*
- * We search all runqueues to find the most busy one.
- * We do this lockless to reduce cache-bouncing overhead,
- * we re-check the 'best' source CPU later on again, with
- * the lock held.
- *
- * We fend off statistical fluctuations in runqueue lengths by
- * saving the runqueue length (as seen by the balancing CPU) during
- * the previous load-balancing operation and using the smaller one
- * of the current and saved lengths. If a runqueue is long enough
- * for a longer amount of time then we recognize it and pull tasks
- * from it.
- *
- * The 'current runqueue length' is a statistical maximum variable,
- * for that one we take the longer one - to avoid fluctuations in
- * the other direction. So for a load-balance to happen it needs
- * stable long runqueue on the target CPU and stable short runqueue
- * on the local runqueue.
- *
- * We make an exception if this CPU is about to become idle - in
- * that case we are less picky about moving a task across CPUs and
- * take what can be taken.
- */
- if (idle || (this_rq->nr_running > this_rq->prev_cpu_load[this_cpu]))
- nr_running = this_rq->nr_running;
- else
- nr_running = this_rq->prev_cpu_load[this_cpu];
-
- busiest = NULL;
- max_load = 1;
- for (i = 0; i < NR_CPUS; i++) {
- if (!cpu_isset(i, cpumask))
- continue;
-
- rq_src = cpu_rq(i);
- if (idle || (rq_src->nr_running < this_rq->prev_cpu_load[i]))
- load = rq_src->nr_running;
- else
- load = this_rq->prev_cpu_load[i];
- this_rq->prev_cpu_load[i] = rq_src->nr_running;
-
- if ((load > max_load) && (rq_src != this_rq)) {
- busiest = rq_src;
- max_load = load;
- }
- }
+ struct sched_domain *tmp, *sd = NULL;
+ int new_cpu, this_cpu = get_cpu();
- if (likely(!busiest))
+ schedstat_inc(this_rq(), sbe_cnt);
+ /* Prefer the current CPU if there's only this task running */
+ if (this_rq()->nr_running <= 1)
goto out;
- *imbalance = max_load - nr_running;
-
- /* It needs an at least ~25% imbalance to trigger balancing. */
- if (!idle && ((*imbalance)*4 < max_load)) {
- busiest = NULL;
- goto out;
- }
+ for_each_domain(this_cpu, tmp)
+ if (tmp->flags & SD_BALANCE_EXEC)
+ sd = tmp;
- nr_running = double_lock_balance(this_rq, busiest, this_cpu,
- idle, nr_running);
- /*
- * Make sure nothing changed since we checked the
- * runqueue length.
- */
- if (busiest->nr_running <= nr_running) {
- spin_unlock(&busiest->lock);
- busiest = NULL;
+ if (sd) {
+ schedstat_inc(sd, sbe_attempts);
+ new_cpu = find_idlest_cpu(current, this_cpu, sd);
+ if (new_cpu != this_cpu) {
+ schedstat_inc(sd, sbe_pushed);
+ put_cpu();
+ sched_migrate_task(current, new_cpu);
+ return;
+ }
}
out:
- return busiest;
+ put_cpu();
}
/*
*/
static inline
void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
- runqueue_t *this_rq, int this_cpu)
+ runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
{
dequeue_task(p, src_array);
- nr_running_dec(src_rq);
+ src_rq->nr_running--;
set_task_cpu(p, this_cpu);
- nr_running_inc(this_rq);
- enqueue_task(p, this_rq->active);
- p->timestamp = sched_clock() -
- (src_rq->timestamp_last_tick - p->timestamp);
+ this_rq->nr_running++;
+ enqueue_task(p, this_array);
+ p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
+ + this_rq->timestamp_last_tick;
/*
* Note that idle threads have a prio of MAX_PRIO, for this test
* to be always true for them.
*/
if (TASK_PREEMPTS_CURR(p, this_rq))
- set_need_resched();
+ resched_task(this_rq->curr);
}
/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static inline
-int can_migrate_task(task_t *tsk, runqueue_t *rq, int this_cpu, int idle)
+int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
+ struct sched_domain *sd, enum idle_type idle)
{
- unsigned long delta = rq->timestamp_last_tick - tsk->timestamp;
-
/*
* We do not migrate tasks that are:
* 1) running (obviously), or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
- if (task_running(rq, tsk))
+ if (task_running(rq, p))
return 0;
- if (!cpu_isset(this_cpu, tsk->cpus_allowed))
- return 0;
- if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks)))
+ if (!cpu_isset(this_cpu, p->cpus_allowed))
return 0;
+
+ /* Aggressive migration if we've failed balancing */
+ if (idle == NEWLY_IDLE ||
+ sd->nr_balance_failed < sd->cache_nice_tries) {
+ if (task_hot(p, rq->timestamp_last_tick, sd))
+ return 0;
+ }
+
return 1;
}
/*
- * Current runqueue is empty, or rebalance tick: if there is an
- * inbalance (current runqueue is too short) then pull from
- * busiest runqueue(s).
+ * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
+ * as part of a balancing operation within "domain". Returns the number of
+ * tasks moved.
*
- * We call this with the current runqueue locked,
- * irqs disabled.
+ * Called with both runqueues locked.
*/
-static void load_balance(runqueue_t *this_rq, int idle, cpumask_t cpumask)
+static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
+ unsigned long max_nr_move, struct sched_domain *sd,
+ enum idle_type idle)
{
- int imbalance, idx, this_cpu = smp_processor_id();
- runqueue_t *busiest;
- prio_array_t *array;
+ prio_array_t *array, *dst_array;
struct list_head *head, *curr;
+ int idx, pulled = 0;
task_t *tmp;
- if (cpu_is_offline(this_cpu))
- goto out;
-
- busiest = find_busiest_queue(this_rq, this_cpu, idle,
- &imbalance, cpumask);
- if (!busiest)
+ if (max_nr_move <= 0 || busiest->nr_running <= 1)
goto out;
- /*
- * We only want to steal a number of tasks equal to 1/2 the imbalance,
- * otherwise we'll just shift the imbalance to the new queue:
- */
- imbalance /= 2;
-
/*
* We first consider expired tasks. Those will likely not be
* executed in the near future, and they are most likely to
* be cache-cold, thus switching CPUs has the least effect
* on them.
*/
- if (busiest->expired->nr_active)
+ if (busiest->expired->nr_active) {
array = busiest->expired;
- else
+ dst_array = this_rq->expired;
+ } else {
array = busiest->active;
+ dst_array = this_rq->active;
+ }
new_array:
/* Start searching at priority 0: */
else
idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
if (idx >= MAX_PRIO) {
- if (array == busiest->expired) {
+ if (array == busiest->expired && busiest->active->nr_active) {
array = busiest->active;
+ dst_array = this_rq->active;
goto new_array;
}
- goto out_unlock;
+ goto out;
}
head = array->queue + idx;
curr = curr->prev;
- if (!can_migrate_task(tmp, busiest, this_cpu, idle)) {
+ if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
if (curr != head)
goto skip_queue;
idx++;
goto skip_bitmap;
}
- pull_task(busiest, array, tmp, this_rq, this_cpu);
- /* Only migrate one task if we are idle */
- if (!idle && --imbalance) {
+ /*
+ * Right now, this is the only place pull_task() is called,
+ * so we can safely collect pull_task() stats here rather than
+ * inside pull_task().
+ */
+ schedstat_inc(this_rq, pt_gained[idle]);
+ schedstat_inc(busiest, pt_lost[idle]);
+
+ pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
+ pulled++;
+
+ /* We only want to steal up to the prescribed number of tasks. */
+ if (pulled < max_nr_move) {
if (curr != head)
goto skip_queue;
idx++;
goto skip_bitmap;
}
-out_unlock:
- spin_unlock(&busiest->lock);
out:
- ;
+ return pulled;
}
/*
- * One of the idle_cpu_tick() and busy_cpu_tick() functions will
- * get called every timer tick, on every CPU. Our balancing action
- * frequency and balancing agressivity depends on whether the CPU is
- * idle or not.
- *
- * busy-rebalance every 200 msecs. idle-rebalance every 1 msec. (or on
- * systems with HZ=100, every 10 msecs.)
- *
- * On NUMA, do a node-rebalance every 400 msecs.
+ * find_busiest_group finds and returns the busiest CPU group within the
+ * domain. It calculates and returns the number of tasks which should be
+ * moved to restore balance via the imbalance parameter.
*/
-#define IDLE_REBALANCE_TICK (HZ/1000 ?: 1)
-#define BUSY_REBALANCE_TICK (HZ/5 ?: 1)
-#define IDLE_NODE_REBALANCE_TICK (IDLE_REBALANCE_TICK * 5)
-#define BUSY_NODE_REBALANCE_TICK (BUSY_REBALANCE_TICK * 2)
-
-#ifdef CONFIG_NUMA
-static void balance_node(runqueue_t *this_rq, int idle, int this_cpu)
+static struct sched_group *
+find_busiest_group(struct sched_domain *sd, int this_cpu,
+ unsigned long *imbalance, enum idle_type idle)
{
- int node = find_busiest_node(cpu_to_node(this_cpu));
+ struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
+ unsigned long max_load, avg_load, total_load, this_load, total_pwr;
- if (node >= 0) {
- cpumask_t cpumask = node_to_cpumask(node);
- cpu_set(this_cpu, cpumask);
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpumask);
- spin_unlock(&this_rq->lock);
- }
-}
-#endif
+ max_load = this_load = total_load = total_pwr = 0;
-static void rebalance_tick(runqueue_t *this_rq, int idle)
-{
-#ifdef CONFIG_NUMA
- int this_cpu = smp_processor_id();
-#endif
- unsigned long j = jiffies;
+ do {
+ cpumask_t tmp;
+ unsigned long load;
+ int local_group;
+ int i, nr_cpus = 0;
+
+ local_group = cpu_isset(this_cpu, group->cpumask);
+
+ /* Tally up the load of all CPUs in the group */
+ avg_load = 0;
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ if (unlikely(cpus_empty(tmp)))
+ goto nextgroup;
+
+ for_each_cpu_mask(i, tmp) {
+ /* Bias balancing toward cpus of our domain */
+ if (local_group)
+ load = target_load(i);
+ else
+ load = source_load(i);
+
+ nr_cpus++;
+ avg_load += load;
+ }
+
+ if (!nr_cpus)
+ goto nextgroup;
+
+ total_load += avg_load;
+ total_pwr += group->cpu_power;
+
+ /* Adjust by relative CPU power of the group */
+ avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
+
+ if (local_group) {
+ this_load = avg_load;
+ this = group;
+ goto nextgroup;
+ } else if (avg_load > max_load) {
+ max_load = avg_load;
+ busiest = group;
+ }
+nextgroup:
+ group = group->next;
+ } while (group != sd->groups);
+
+ if (!busiest || this_load >= max_load)
+ goto out_balanced;
+
+ avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
+
+ if (this_load >= avg_load ||
+ 100*max_load <= sd->imbalance_pct*this_load)
+ goto out_balanced;
/*
- * First do inter-node rebalancing, then intra-node rebalancing,
- * if both events happen in the same tick. The inter-node
- * rebalancing does not necessarily have to create a perfect
- * balance within the node, since we load-balance the most loaded
- * node with the current CPU. (ie. other CPUs in the local node
- * are not balanced.)
+ * We're trying to get all the cpus to the average_load, so we don't
+ * want to push ourselves above the average load, nor do we wish to
+ * reduce the max loaded cpu below the average load, as either of these
+ * actions would just result in more rebalancing later, and ping-pong
+ * tasks around. Thus we look for the minimum possible imbalance.
+ * Negative imbalances (*we* are more loaded than anyone else) will
+ * be counted as no imbalance for these purposes -- we can't fix that
+ * by pulling tasks to us. Be careful of negative numbers as they'll
+ * appear as very large values with unsigned longs.
*/
- if (idle) {
-#ifdef CONFIG_NUMA
- if (!(j % IDLE_NODE_REBALANCE_TICK))
- balance_node(this_rq, idle, this_cpu);
-#endif
- if (!(j % IDLE_REBALANCE_TICK)) {
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
- spin_unlock(&this_rq->lock);
+ *imbalance = min(max_load - avg_load, avg_load - this_load);
+
+ /* How much load to actually move to equalise the imbalance */
+ *imbalance = (*imbalance * min(busiest->cpu_power, this->cpu_power))
+ / SCHED_LOAD_SCALE;
+
+ if (*imbalance < SCHED_LOAD_SCALE - 1) {
+ unsigned long pwr_now = 0, pwr_move = 0;
+ unsigned long tmp;
+
+ if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
+ *imbalance = 1;
+ return busiest;
}
- return;
+
+ /*
+ * OK, we don't have enough imbalance to justify moving tasks,
+ * however we may be able to increase total CPU power used by
+ * moving them.
+ */
+
+ pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
+ pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
+ pwr_now /= SCHED_LOAD_SCALE;
+
+ /* Amount of load we'd subtract */
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
+ if (max_load > tmp)
+ pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
+ max_load - tmp);
+
+ /* Amount of load we'd add */
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
+ if (max_load < tmp)
+ tmp = max_load;
+ pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
+ pwr_move /= SCHED_LOAD_SCALE;
+
+ /* Move if we gain another 8th of a CPU worth of throughput */
+ if (pwr_move < pwr_now + SCHED_LOAD_SCALE / 8)
+ goto out_balanced;
+
+ *imbalance = 1;
+ return busiest;
}
-#ifdef CONFIG_NUMA
- if (!(j % BUSY_NODE_REBALANCE_TICK))
- balance_node(this_rq, idle, this_cpu);
-#endif
- if (!(j % BUSY_REBALANCE_TICK)) {
- spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
- spin_unlock(&this_rq->lock);
+
+ /* Get rid of the scaling factor, rounding down as we divide */
+ *imbalance = (*imbalance + 1) / SCHED_LOAD_SCALE;
+
+ return busiest;
+
+out_balanced:
+ if (busiest && (idle == NEWLY_IDLE ||
+ (idle == IDLE && max_load > SCHED_LOAD_SCALE)) ) {
+ *imbalance = 1;
+ return busiest;
}
+
+ *imbalance = 0;
+ return NULL;
}
-#else
+
/*
- * on UP we do not need to balance between CPUs:
+ * find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
-static inline void rebalance_tick(runqueue_t *this_rq, int idle)
+static runqueue_t *find_busiest_queue(struct sched_group *group)
{
-}
-#endif
+ cpumask_t tmp;
+ unsigned long load, max_load = 0;
+ runqueue_t *busiest = NULL;
+ int i;
-DEFINE_PER_CPU(struct kernel_stat, kstat);
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ for_each_cpu_mask(i, tmp) {
+ load = source_load(i);
-EXPORT_PER_CPU_SYMBOL(kstat);
+ if (load > max_load) {
+ max_load = load;
+ busiest = cpu_rq(i);
+ }
+ }
+
+ return busiest;
+}
/*
- * We place interactive tasks back into the active array, if possible.
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
*
- * To guarantee that this does not starve expired tasks we ignore the
- * interactivity of a task if the first expired task had to wait more
+ * Called with this_rq unlocked.
+ */
+static int load_balance(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd, enum idle_type idle)
+{
+ struct sched_group *group;
+ runqueue_t *busiest;
+ unsigned long imbalance;
+ int nr_moved;
+
+ spin_lock(&this_rq->lock);
+ schedstat_inc(sd, lb_cnt[idle]);
+
+ group = find_busiest_group(sd, this_cpu, &imbalance, idle);
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[idle]);
+ goto out_balanced;
+ }
+
+ busiest = find_busiest_queue(group);
+ if (!busiest) {
+ schedstat_inc(sd, lb_nobusyq[idle]);
+ goto out_balanced;
+ }
+
+ /*
+ * This should be "impossible", but since load
+ * balancing is inherently racy and statistical,
+ * it could happen in theory.
+ */
+ if (unlikely(busiest == this_rq)) {
+ WARN_ON(1);
+ goto out_balanced;
+ }
+
+ schedstat_add(sd, lb_imbalance[idle], imbalance);
+
+ nr_moved = 0;
+ if (busiest->nr_running > 1) {
+ /*
+ * Attempt to move tasks. If find_busiest_group has found
+ * an imbalance but busiest->nr_running <= 1, the group is
+ * still unbalanced. nr_moved simply stays zero, so it is
+ * correctly treated as an imbalance.
+ */
+ double_lock_balance(this_rq, busiest);
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, idle);
+ spin_unlock(&busiest->lock);
+ }
+ spin_unlock(&this_rq->lock);
+
+ if (!nr_moved) {
+ schedstat_inc(sd, lb_failed[idle]);
+ sd->nr_balance_failed++;
+
+ if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
+ int wake = 0;
+
+ spin_lock(&busiest->lock);
+ if (!busiest->active_balance) {
+ busiest->active_balance = 1;
+ busiest->push_cpu = this_cpu;
+ wake = 1;
+ }
+ spin_unlock(&busiest->lock);
+ if (wake)
+ wake_up_process(busiest->migration_thread);
+
+ /*
+ * We've kicked active balancing, reset the failure
+ * counter.
+ */
+ sd->nr_balance_failed = sd->cache_nice_tries;
+ }
+ } else
+ sd->nr_balance_failed = 0;
+
+ /* We were unbalanced, so reset the balancing interval */
+ sd->balance_interval = sd->min_interval;
+
+ return nr_moved;
+
+out_balanced:
+ spin_unlock(&this_rq->lock);
+
+ /* tune up the balancing interval */
+ if (sd->balance_interval < sd->max_interval)
+ sd->balance_interval *= 2;
+
+ return 0;
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ *
+ * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
+ * this_rq is locked.
+ */
+static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
+ struct sched_domain *sd)
+{
+ struct sched_group *group;
+ runqueue_t *busiest = NULL;
+ unsigned long imbalance;
+ int nr_moved = 0;
+
+ schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
+ group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
+ if (!group) {
+ schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
+ goto out;
+ }
+
+ busiest = find_busiest_queue(group);
+ if (!busiest || busiest == this_rq) {
+ schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
+ goto out;
+ }
+
+ /* Attempt to move tasks */
+ double_lock_balance(this_rq, busiest);
+
+ schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
+ nr_moved = move_tasks(this_rq, this_cpu, busiest,
+ imbalance, sd, NEWLY_IDLE);
+ if (!nr_moved)
+ schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
+
+ spin_unlock(&busiest->lock);
+
+out:
+ return nr_moved;
+}
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd;
+
+ for_each_domain(this_cpu, sd) {
+ if (sd->flags & SD_BALANCE_NEWIDLE) {
+ if (load_balance_newidle(this_cpu, this_rq, sd)) {
+ /* We've pulled tasks over so stop searching */
+ break;
+ }
+ }
+ }
+}
+
+/*
+ * active_load_balance is run by migration threads. It pushes a running
+ * task off the cpu. It can be required to correctly have at least 1 task
+ * running on each physical CPU where possible, and not have a physical /
+ * logical imbalance.
+ *
+ * Called with busiest locked.
+ */
+static void active_load_balance(runqueue_t *busiest, int busiest_cpu)
+{
+ struct sched_domain *sd;
+ struct sched_group *group, *busy_group;
+ int i;
+
+ schedstat_inc(busiest, alb_cnt);
+ if (busiest->nr_running <= 1)
+ return;
+
+ for_each_domain(busiest_cpu, sd)
+ if (cpu_isset(busiest->push_cpu, sd->span))
+ break;
+ if (!sd)
+ return;
+
+ group = sd->groups;
+ while (!cpu_isset(busiest_cpu, group->cpumask))
+ group = group->next;
+ busy_group = group;
+
+ group = sd->groups;
+ do {
+ cpumask_t tmp;
+ runqueue_t *rq;
+ int push_cpu = 0;
+
+ if (group == busy_group)
+ goto next_group;
+
+ cpus_and(tmp, group->cpumask, cpu_online_map);
+ if (!cpus_weight(tmp))
+ goto next_group;
+
+ for_each_cpu_mask(i, tmp) {
+ if (!idle_cpu(i))
+ goto next_group;
+ push_cpu = i;
+ }
+
+ rq = cpu_rq(push_cpu);
+
+ /*
+ * This condition is "impossible", but since load
+ * balancing is inherently a bit racy and statistical,
+ * it can trigger.. Reported by Bjorn Helgaas on a
+ * 128-cpu setup.
+ */
+ if (unlikely(busiest == rq))
+ goto next_group;
+ double_lock_balance(busiest, rq);
+ if (move_tasks(rq, push_cpu, busiest, 1, sd, IDLE)) {
+ schedstat_inc(busiest, alb_lost);
+ schedstat_inc(rq, alb_gained);
+ } else {
+ schedstat_inc(busiest, alb_failed);
+ }
+ spin_unlock(&rq->lock);
+next_group:
+ group = group->next;
+ } while (group != sd->groups);
+}
+
+/*
+ * rebalance_tick will get called every timer tick, on every CPU.
+ *
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in arch_init_sched_domains.
+ */
+
+/* Don't have all balancing operations going off at once */
+#define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
+
+static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
+ enum idle_type idle)
+{
+ unsigned long old_load, this_load;
+ unsigned long j = jiffies + CPU_OFFSET(this_cpu);
+ struct sched_domain *sd;
+
+ /* Update our load */
+ old_load = this_rq->cpu_load;
+ this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
+ /*
+ * Round up the averaging division if load is increasing. This
+ * prevents us from getting stuck on 9 if the load is 10, for
+ * example.
+ */
+ if (this_load > old_load)
+ old_load++;
+ this_rq->cpu_load = (old_load + this_load) / 2;
+
+ for_each_domain(this_cpu, sd) {
+ unsigned long interval = sd->balance_interval;
+
+ if (idle != IDLE)
+ interval *= sd->busy_factor;
+
+ /* scale ms to jiffies */
+ interval = msecs_to_jiffies(interval);
+ if (unlikely(!interval))
+ interval = 1;
+
+ if (j - sd->last_balance >= interval) {
+ if (load_balance(this_cpu, this_rq, sd, idle)) {
+ /* We've pulled tasks over so no longer idle */
+ idle = NOT_IDLE;
+ }
+ sd->last_balance += interval;
+ }
+ }
+}
+#else
+/*
+ * on UP we do not need to balance between CPUs:
+ */
+static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
+{
+}
+static inline void idle_balance(int cpu, runqueue_t *rq)
+{
+}
+#endif
+
+static inline int wake_priority_sleeper(runqueue_t *rq)
+{
+ int ret = 0;
+#ifdef CONFIG_SCHED_SMT
+ spin_lock(&rq->lock);
+ /*
+ * If an SMT sibling task has been put to sleep for priority
+ * reasons reschedule the idle task to see if it can now run.
+ */
+ if (rq->nr_running) {
+ resched_task(rq->idle);
+ ret = 1;
+ }
+ spin_unlock(&rq->lock);
+#endif
+ return ret;
+}
+
+DEFINE_PER_CPU(struct kernel_stat, kstat);
+
+EXPORT_PER_CPU_SYMBOL(kstat);
+
+/*
+ * We place interactive tasks back into the active array, if possible.
+ *
+ * To guarantee that this does not starve expired tasks we ignore the
+ * interactivity of a task if the first expired task had to wait more
* than a 'reasonable' amount of time. This deadline timeout is
* load-dependent, as the frequency of array switched decreases with
* increasing number of running tasks. We also ignore the interactivity
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
runqueue_t *rq = this_rq();
task_t *p = current;
+ struct vx_info *vxi = p->vx_info;
rq->timestamp_last_tick = sched_clock();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, user_ticks);
+ if (vxi) {
+ vxi->sched.cpu[cpu].user_ticks += user_ticks;
+ vxi->sched.cpu[cpu].sys_ticks += sys_ticks;
+ }
+
/* note: this timer irq context must be accounted for as well */
if (hardirq_count() - HARDIRQ_OFFSET) {
cpustat->irq += sys_ticks;
if (p == rq->idle) {
if (atomic_read(&rq->nr_iowait) > 0)
cpustat->iowait += sys_ticks;
+ // vx_cpustat_acc(vxi, iowait, cpu, cpustat, sys_ticks);
else
cpustat->idle += sys_ticks;
- rebalance_tick(rq, 1);
+ // vx_cpustat_acc(vxi, idle, cpu, cpustat, sys_ticks);
+
+ if (wake_priority_sleeper(rq))
+ goto out;
+
+#ifdef CONFIG_VSERVER_HARDCPU_IDLE
+ if (!--rq->idle_tokens && !list_empty(&rq->hold_queue))
+ set_need_resched();
+#endif
+ rebalance_tick(cpu, rq, IDLE);
return;
}
if (TASK_NICE(p) > 0)
* timeslice. This makes it possible for interactive tasks
* to use up their timeslices at their highest priority levels.
*/
- if (unlikely(rt_task(p))) {
+ if (rt_task(p)) {
/*
* RR tasks need a special form of timeslice management.
* FIFO tasks have no timeslices.
}
goto out_unlock;
}
- if (!--p->time_slice) {
+ if (vx_need_resched(p)) {
dequeue_task(p, rq->active);
set_tsk_need_resched(p);
p->prio = effective_prio(p);
out_unlock:
spin_unlock(&rq->lock);
out:
- rebalance_tick(rq, 0);
+ rebalance_tick(cpu, rq, NOT_IDLE);
+}
+
+#ifdef CONFIG_SCHED_SMT
+static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd = this_rq->sd;
+ cpumask_t sibling_map;
+ int i;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return;
+
+ /*
+ * Unlock the current runqueue because we have to lock in
+ * CPU order to avoid deadlocks. Caller knows that we might
+ * unlock. We keep IRQs disabled.
+ */
+ spin_unlock(&this_rq->lock);
+
+ cpus_and(sibling_map, sd->span, cpu_online_map);
+
+ for_each_cpu_mask(i, sibling_map)
+ spin_lock(&cpu_rq(i)->lock);
+ /*
+ * We clear this CPU from the mask. This both simplifies the
+ * inner loop and keps this_rq locked when we exit:
+ */
+ cpu_clear(this_cpu, sibling_map);
+
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq = cpu_rq(i);
+
+ /*
+ * If an SMT sibling task is sleeping due to priority
+ * reasons wake it up now.
+ */
+ if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running)
+ resched_task(smt_rq->idle);
+ }
+
+ for_each_cpu_mask(i, sibling_map)
+ spin_unlock(&cpu_rq(i)->lock);
+ /*
+ * We exit with this_cpu's rq still held and IRQs
+ * still disabled:
+ */
+}
+
+static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
+{
+ struct sched_domain *sd = this_rq->sd;
+ cpumask_t sibling_map;
+ prio_array_t *array;
+ int ret = 0, i;
+ task_t *p;
+
+ if (!(sd->flags & SD_SHARE_CPUPOWER))
+ return 0;
+
+ /*
+ * The same locking rules and details apply as for
+ * wake_sleeping_dependent():
+ */
+ spin_unlock(&this_rq->lock);
+ cpus_and(sibling_map, sd->span, cpu_online_map);
+ for_each_cpu_mask(i, sibling_map)
+ spin_lock(&cpu_rq(i)->lock);
+ cpu_clear(this_cpu, sibling_map);
+
+ /*
+ * Establish next task to be run - it might have gone away because
+ * we released the runqueue lock above:
+ */
+ if (!this_rq->nr_running)
+ goto out_unlock;
+ array = this_rq->active;
+ if (!array->nr_active)
+ array = this_rq->expired;
+ BUG_ON(!array->nr_active);
+
+ p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next,
+ task_t, run_list);
+
+ for_each_cpu_mask(i, sibling_map) {
+ runqueue_t *smt_rq = cpu_rq(i);
+ task_t *smt_curr = smt_rq->curr;
+
+ /*
+ * If a user task with lower static priority than the
+ * running task on the SMT sibling is trying to schedule,
+ * delay it till there is proportionately less timeslice
+ * left of the sibling task to prevent a lower priority
+ * task from using an unfair proportion of the
+ * physical cpu's resources. -ck
+ */
+ if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(p) || rt_task(smt_curr)) &&
+ p->mm && smt_curr->mm && !rt_task(p))
+ ret = 1;
+
+ /*
+ * Reschedule a lower priority task on the SMT sibling,
+ * or wake it up if it has been put to sleep for priority
+ * reasons.
+ */
+ if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) >
+ task_timeslice(smt_curr) || rt_task(p)) &&
+ smt_curr->mm && p->mm && !rt_task(smt_curr)) ||
+ (smt_curr == smt_rq->idle && smt_rq->nr_running))
+ resched_task(smt_curr);
+ }
+out_unlock:
+ for_each_cpu_mask(i, sibling_map)
+ spin_unlock(&cpu_rq(i)->lock);
+ return ret;
+}
+#else
+static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
+{
}
+static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
+{
+ return 0;
+}
+#endif
+
/*
* schedule() is the main scheduler function.
*/
struct list_head *queue;
unsigned long long now;
unsigned long run_time;
- int idx;
+#ifdef CONFIG_VSERVER_HARDCPU
+ struct vx_info *vxi;
+ int maxidle = -HZ;
+#endif
+ int cpu, idx;
/*
* Test if we are atomic. Since do_exit() needs to call into
prev = current;
rq = this_rq();
+ /*
+ * The idle thread is not allowed to schedule!
+ * Remove this check after it has been exercised a bit.
+ */
+ if (unlikely(current == rq->idle) && current->state != TASK_RUNNING) {
+ printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ dump_stack();
+ }
+
release_kernel_lock(prev);
+ schedstat_inc(rq, sched_cnt);
now = sched_clock();
if (likely(now - prev->timestamp < NS_MAX_SLEEP_AVG))
run_time = now - prev->timestamp;
deactivate_task(prev, rq);
}
- if (unlikely(!rq->nr_running)) {
-#ifdef CONFIG_SMP
- load_balance(rq, 1, cpu_to_node_mask(smp_processor_id()));
+#ifdef CONFIG_VSERVER_HARDCPU
+ if (!list_empty(&rq->hold_queue)) {
+ struct list_head *l, *n;
+ int ret;
+
+ vxi = NULL;
+ list_for_each_safe(l, n, &rq->hold_queue) {
+ next = list_entry(l, task_t, run_list);
+ if (vxi == next->vx_info)
+ continue;
+
+ vxi = next->vx_info;
+ ret = vx_tokens_recalc(vxi);
+ // tokens = vx_tokens_avail(next);
+
+ if (ret > 0) {
+ list_del(&next->run_list);
+ next->state &= ~TASK_ONHOLD;
+ // one less waiting
+ vx_onhold_dec(vxi);
+ array = rq->expired;
+ next->prio = MAX_PRIO-1;
+ enqueue_task(next, array);
+ rq->nr_running++;
+ if (next->static_prio < rq->best_expired_prio)
+ rq->best_expired_prio = next->static_prio;
+
+ // printk("··· %8lu unhold %p [%d]\n", jiffies, next, next->prio);
+ break;
+ }
+ if ((ret < 0) && (maxidle < ret))
+ maxidle = ret;
+ }
+ }
+ rq->idle_tokens = -maxidle;
+
+pick_next:
#endif
+
+ cpu = smp_processor_id();
+ if (unlikely(!rq->nr_running)) {
+go_idle:
+ idle_balance(cpu, rq);
if (!rq->nr_running) {
next = rq->idle;
rq->expired_timestamp = 0;
+ wake_sleeping_dependent(cpu, rq);
+ /*
+ * wake_sleeping_dependent() might have released
+ * the runqueue, so break out if we got new
+ * tasks meanwhile:
+ */
+ if (!rq->nr_running)
+ goto switch_tasks;
+ }
+ } else {
+ if (dependent_sleeper(cpu, rq)) {
+ schedstat_inc(rq, sched_goidle);
+ next = rq->idle;
goto switch_tasks;
}
+ /*
+ * dependent_sleeper() releases and reacquires the runqueue
+ * lock, hence go into the idle loop if the rq went
+ * empty meanwhile:
+ */
+ if (unlikely(!rq->nr_running))
+ goto go_idle;
}
array = rq->active;
/*
* Switch the active and expired arrays.
*/
+ schedstat_inc(rq, sched_switch);
rq->active = rq->expired;
rq->expired = array;
array = rq->active;
rq->expired_timestamp = 0;
rq->best_expired_prio = MAX_PRIO;
- }
+ } else
+ schedstat_inc(rq, sched_noswitch);
idx = sched_find_first_bit(array->bitmap);
queue = array->queue + idx;
next = list_entry(queue->next, task_t, run_list);
+#ifdef CONFIG_VSERVER_HARDCPU
+ vxi = next->vx_info;
+ if (vx_info_flags(vxi, VXF_SCHED_PAUSE|VXF_SCHED_HARD, 0)) {
+ int ret = vx_tokens_recalc(vxi);
+
+ if (unlikely(ret <= 0)) {
+ if (ret && (rq->idle_tokens > -ret))
+ rq->idle_tokens = -ret;
+ __deactivate_task(next, rq);
+ recalc_task_prio(next, now);
+ // a new one on hold
+ vx_onhold_inc(vxi);
+ next->state |= TASK_ONHOLD;
+ list_add_tail(&next->run_list, &rq->hold_queue);
+ //printk("··· %8lu hold %p [%d]\n", jiffies, next, next->prio);
+ goto pick_next;
+ }
+ }
+#endif
+
if (!rt_task(next) && next->activated > 0) {
unsigned long long delta = now - next->timestamp;
switch_tasks:
prefetch(next);
clear_tsk_need_resched(prev);
- RCU_qsctr(task_cpu(prev))++;
+ rcu_qsctr_inc(task_cpu(prev));
prev->sleep_avg -= run_time;
if ((long)prev->sleep_avg <= 0) {
if (!(HIGH_CREDIT(prev) || LOW_CREDIT(prev)))
prev->interactive_credit--;
}
- prev->timestamp = now;
+ prev->timestamp = prev->last_ran = now;
+ sched_info_switch(prev, next);
if (likely(prev != next)) {
next->timestamp = now;
rq->nr_switches++;
reacquire_kernel_lock(current);
preempt_enable_no_resched();
- if (test_thread_flag(TIF_NEED_RESCHED))
+ if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
goto need_resched;
}
EXPORT_SYMBOL(preempt_schedule);
#endif /* CONFIG_PREEMPT */
-int default_wake_function(wait_queue_t *curr, unsigned mode, int sync)
+int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
{
task_t *p = curr->task;
return try_to_wake_up(p, mode, sync);
* zero in this (rare) case, and we handle it by continuing to scan the queue.
*/
static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
- int nr_exclusive, int sync)
+ int nr_exclusive, int sync, void *key)
{
struct list_head *tmp, *next;
unsigned flags;
curr = list_entry(tmp, wait_queue_t, task_list);
flags = curr->flags;
- if (curr->func(curr, mode, sync) &&
+ if (curr->func(curr, mode, sync, key) &&
(flags & WQ_FLAG_EXCLUSIVE) &&
!--nr_exclusive)
break;
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
*/
-void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
+void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
+ int nr_exclusive, void *key)
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
- __wake_up_common(q, mode, nr_exclusive, 0);
+ __wake_up_common(q, mode, nr_exclusive, 0, key);
spin_unlock_irqrestore(&q->lock, flags);
}
*/
void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
{
- __wake_up_common(q, mode, 1, 0);
+ __wake_up_common(q, mode, 1, 0, NULL);
}
/**
void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
{
unsigned long flags;
+ int sync = 1;
if (unlikely(!q))
return;
+ if (unlikely(!nr_exclusive))
+ sync = 0;
+
spin_lock_irqsave(&q->lock, flags);
- if (likely(nr_exclusive))
- __wake_up_common(q, mode, nr_exclusive, 1);
- else
- __wake_up_common(q, mode, nr_exclusive, 0);
+ __wake_up_common(q, mode, nr_exclusive, sync, NULL);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
spin_lock_irqsave(&x->wait.lock, flags);
x->done++;
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
- 1, 0);
+ 1, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete);
spin_lock_irqsave(&x->wait.lock, flags);
x->done += UINT_MAX/2;
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
- 0, 0);
+ 0, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete_all);
EXPORT_SYMBOL(set_user_nice);
-#ifndef __alpha__
+#ifdef __ARCH_WANT_SYS_NICE
/*
* sys_nice - change the priority of the current process.
* and we have a single winner.
*/
if (increment < 0) {
+ if (vx_flags(VXF_IGNEG_NICE, 0))
+ return 0;
if (!capable(CAP_SYS_NICE))
return -EPERM;
if (increment < -40)
* RT tasks are offset by -200. Normal tasks are centered
* around 0, value goes from -16 to +15.
*/
-int task_prio(task_t *p)
+int task_prio(const task_t *p)
{
return p->prio - MAX_RT_PRIO;
}
* task_nice - return the nice value of a given task.
* @p: the task in question.
*/
-int task_nice(task_t *p)
+int task_nice(const task_t *p)
{
return TASK_NICE(p);
}
policy != SCHED_NORMAL)
goto out_unlock;
}
+ profile_hit(SCHED_PROFILING, __builtin_return_address(0));
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are
oldprio = p->prio;
__setscheduler(p, policy, lp.sched_priority);
if (array) {
+ vx_activate_task(p);
__activate_task(p, task_rq(p));
/*
* Reschedule if we are currently running on this runqueue and
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
- } else if (p->prio < rq->curr->prio)
+ } else if (TASK_PREEMPTS_CURR(p, rq))
resched_task(rq->curr);
}
return retval;
}
-/**
- * sys_sched_setaffinity - set the cpu affinity of a process
- * @pid: pid of the process
- * @len: length in bytes of the bitmask pointed to by user_mask_ptr
- * @user_mask_ptr: user-space pointer to the new cpu mask
- */
-asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
- unsigned long __user *user_mask_ptr)
+long sched_setaffinity(pid_t pid, cpumask_t new_mask)
{
- cpumask_t new_mask;
- int retval;
task_t *p;
-
- if (len < sizeof(new_mask))
- return -EINVAL;
-
- if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
- return -EFAULT;
+ int retval;
lock_cpu_hotplug();
read_lock(&tasklist_lock);
return retval;
}
+static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
+ cpumask_t *new_mask)
+{
+ if (len < sizeof(cpumask_t)) {
+ memset(new_mask, 0, sizeof(cpumask_t));
+ } else if (len > sizeof(cpumask_t)) {
+ len = sizeof(cpumask_t);
+ }
+ return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
+}
+
/**
- * sys_sched_getaffinity - get the cpu affinity of a process
+ * sys_sched_setaffinity - set the cpu affinity of a process
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
- * @user_mask_ptr: user-space pointer to hold the current cpu mask
+ * @user_mask_ptr: user-space pointer to the new cpu mask
*/
-asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
+asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
unsigned long __user *user_mask_ptr)
{
- unsigned int real_len;
- cpumask_t mask;
+ cpumask_t new_mask;
int retval;
- task_t *p;
- real_len = sizeof(mask);
- if (len < real_len)
- return -EINVAL;
+ retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
+ if (retval)
+ return retval;
+
+ return sched_setaffinity(pid, new_mask);
+}
+
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+
+cpumask_t cpu_present_map;
+EXPORT_SYMBOL(cpu_present_map);
+
+#ifndef CONFIG_SMP
+cpumask_t cpu_online_map = CPU_MASK_ALL;
+cpumask_t cpu_possible_map = CPU_MASK_ALL;
+#endif
+
+long sched_getaffinity(pid_t pid, cpumask_t *mask)
+{
+ int retval;
+ task_t *p;
+ lock_cpu_hotplug();
read_lock(&tasklist_lock);
retval = -ESRCH;
goto out_unlock;
retval = 0;
- cpus_and(mask, p->cpus_allowed, cpu_possible_map);
+ cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
out_unlock:
read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
if (retval)
return retval;
- if (copy_to_user(user_mask_ptr, &mask, real_len))
+
+ return 0;
+}
+
+/**
+ * sys_sched_getaffinity - get the cpu affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to hold the current cpu mask
+ */
+asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
+ unsigned long __user *user_mask_ptr)
+{
+ int ret;
+ cpumask_t mask;
+
+ if (len < sizeof(cpumask_t))
+ return -EINVAL;
+
+ ret = sched_getaffinity(pid, &mask);
+ if (ret < 0)
+ return ret;
+
+ if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
return -EFAULT;
- return real_len;
+
+ return sizeof(cpumask_t);
}
/**
{
runqueue_t *rq = this_rq_lock();
prio_array_t *array = current->array;
+ prio_array_t *target = rq->expired;
+ schedstat_inc(rq, yld_cnt);
/*
* We implement yielding by moving the task into the expired
* queue.
* (special rule: RT tasks will just roundrobin in the active
* array.)
*/
- if (likely(!rt_task(current))) {
- dequeue_task(current, array);
- enqueue_task(current, rq->expired);
- } else {
- list_del(¤t->run_list);
- list_add_tail(¤t->run_list, array->queue + current->prio);
- }
+ if (rt_task(current))
+ target = rq->active;
+
+ if (current->array->nr_active == 1) {
+ schedstat_inc(rq, yld_act_empty);
+ if (!rq->expired->nr_active)
+ schedstat_inc(rq, yld_both_empty);
+ } else if (!rq->expired->nr_active)
+ schedstat_inc(rq, yld_exp_empty);
+
+ dequeue_task(current, array);
+ enqueue_task(current, target);
+
/*
* Since we are going to call schedule() anyway, there's
- * no need to preempt:
+ * no need to preempt or enable interrupts:
*/
_raw_spin_unlock(&rq->lock);
preempt_enable_no_resched();
task_t *relative;
unsigned state;
unsigned long free = 0;
- static const char *stat_nam[] = { "R", "S", "D", "T", "Z", "W" };
+ static const char *stat_nam[] = { "R", "S", "D", "T", "t", "Z", "X" };
printk("%-13.13s ", p->comm);
state = p->state ? __ffs(p->state) + 1 : 0;
read_unlock(&tasklist_lock);
}
-void __init init_idle(task_t *idle, int cpu)
+void __devinit init_idle(task_t *idle, int cpu)
{
- runqueue_t *idle_rq = cpu_rq(cpu), *rq = cpu_rq(task_cpu(idle));
+ runqueue_t *rq = cpu_rq(cpu);
unsigned long flags;
- local_irq_save(flags);
- double_rq_lock(idle_rq, rq);
-
- idle_rq->curr = idle_rq->idle = idle;
- deactivate_task(idle, rq);
+ idle->sleep_avg = 0;
+ idle->interactive_credit = 0;
idle->array = NULL;
idle->prio = MAX_PRIO;
idle->state = TASK_RUNNING;
set_task_cpu(idle, cpu);
- double_rq_unlock(idle_rq, rq);
+
+ spin_lock_irqsave(&rq->lock, flags);
+ rq->curr = rq->idle = idle;
set_tsk_need_resched(idle);
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&rq->lock, flags);
/* Set the preempt count _outside_ the spinlocks! */
#ifdef CONFIG_PREEMPT
}
/*
- * In a system that switches off the HZ timer idle_cpu_mask
+ * In a system that switches off the HZ timer nohz_cpu_mask
* indicates which cpus entered this state. This is used
* in the rcu update to wait only for active cpus. For system
- * which do not switch off the HZ timer idle_cpu_mask should
+ * which do not switch off the HZ timer nohz_cpu_mask should
* always be CPU_MASK_NONE.
*/
-cpumask_t idle_cpu_mask = CPU_MASK_NONE;
+cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
#ifdef CONFIG_SMP
/*
runqueue_t *rq;
rq = task_rq_lock(p, &flags);
- if (any_online_cpu(new_mask) == NR_CPUS) {
+ if (!cpus_intersects(new_mask, cpu_online_map)) {
ret = -EINVAL;
goto out;
}
- if (__set_cpus_allowed(p, new_mask, &req)) {
+ p->cpus_allowed = new_mask;
+ /* Can the task run on the task's current CPU? If so, we're done */
+ if (cpu_isset(task_cpu(p), new_mask))
+ goto out;
+
+ if (migrate_task(p, any_online_cpu(new_mask), &req)) {
/* Need help from migration thread: drop lock and wait. */
task_rq_unlock(rq, &flags);
wake_up_process(rq->migration_thread);
wait_for_completion(&req.done);
+ tlb_migrate_finish(p->mm);
return 0;
}
out:
EXPORT_SYMBOL_GPL(set_cpus_allowed);
-/* Move (not current) task off this cpu, onto dest cpu. */
-static void move_task_away(struct task_struct *p, int dest_cpu)
+/*
+ * Move (not current) task off this cpu, onto dest cpu. We're doing
+ * this because either it can't run here any more (set_cpus_allowed()
+ * away from this CPU, or CPU going down), or because we're
+ * attempting to rebalance this task on exec (sched_exec).
+ *
+ * So we race with normal scheduler movements, but that's OK, as long
+ * as the task is no longer on this CPU.
+ */
+static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
- runqueue_t *rq_dest;
+ runqueue_t *rq_dest, *rq_src;
+ if (unlikely(cpu_is_offline(dest_cpu)))
+ return;
+
+ rq_src = cpu_rq(src_cpu);
rq_dest = cpu_rq(dest_cpu);
- double_rq_lock(this_rq(), rq_dest);
- if (task_cpu(p) != smp_processor_id())
- goto out; /* Already moved */
+ double_rq_lock(rq_src, rq_dest);
+ /* Already moved. */
+ if (task_cpu(p) != src_cpu)
+ goto out;
+ /* Affinity changed (again). */
+ if (!cpu_isset(dest_cpu, p->cpus_allowed))
+ goto out;
set_task_cpu(p, dest_cpu);
if (p->array) {
- deactivate_task(p, this_rq());
- activate_task(p, rq_dest);
- if (p->prio < rq_dest->curr->prio)
+ /*
+ * Sync timestamp with rq_dest's before activating.
+ * The same thing could be achieved by doing this step
+ * afterwards, and pretending it was a local activate.
+ * This way is cleaner and logically correct.
+ */
+ p->timestamp = p->timestamp - rq_src->timestamp_last_tick
+ + rq_dest->timestamp_last_tick;
+ deactivate_task(p, rq_src);
+ activate_task(p, rq_dest, 0);
+ if (TASK_PREEMPTS_CURR(p, rq_dest))
resched_task(rq_dest->curr);
}
- p->timestamp = rq_dest->timestamp_last_tick;
out:
- double_rq_unlock(this_rq(), rq_dest);
+ double_rq_unlock(rq_src, rq_dest);
}
/*
rq = cpu_rq(cpu);
BUG_ON(rq->migration_thread != current);
+ set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
struct list_head *head;
migration_req_t *req;
refrigerator(PF_FREEZE);
spin_lock_irq(&rq->lock);
+
+ if (cpu_is_offline(cpu)) {
+ spin_unlock_irq(&rq->lock);
+ goto wait_to_die;
+ }
+
+ if (rq->active_balance) {
+ active_load_balance(rq, cpu);
+ rq->active_balance = 0;
+ }
+
head = &rq->migration_queue;
- current->state = TASK_INTERRUPTIBLE;
+
if (list_empty(head)) {
spin_unlock_irq(&rq->lock);
schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
continue;
}
req = list_entry(head->next, migration_req_t, list);
list_del_init(head->next);
- spin_unlock(&rq->lock);
- move_task_away(req->task,
- any_online_cpu(req->task->cpus_allowed));
- local_irq_enable();
+ if (req->type == REQ_MOVE_TASK) {
+ spin_unlock(&rq->lock);
+ __migrate_task(req->task, smp_processor_id(),
+ req->dest_cpu);
+ local_irq_enable();
+ } else if (req->type == REQ_SET_DOMAIN) {
+ rq->sd = req->sd;
+ spin_unlock_irq(&rq->lock);
+ } else {
+ spin_unlock_irq(&rq->lock);
+ WARN_ON(1);
+ }
+
complete(&req->done);
}
+ __set_current_state(TASK_RUNNING);
+ return 0;
+
+wait_to_die:
+ /* Wait for kthread_stop */
+ set_current_state(TASK_INTERRUPTIBLE);
+ while (!kthread_should_stop()) {
+ schedule();
+ set_current_state(TASK_INTERRUPTIBLE);
+ }
+ __set_current_state(TASK_RUNNING);
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
-/* migrate_all_tasks - function to migrate all the tasks from the
- * current cpu caller must have already scheduled this to the target
- * cpu via set_cpus_allowed. Machine is stopped. */
-void migrate_all_tasks(void)
+/* Figure out where task on dead CPU should go, use force if neccessary. */
+static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk)
{
- struct task_struct *tsk, *t;
- int dest_cpu, src_cpu;
- unsigned int node;
+ int dest_cpu;
+ cpumask_t mask;
- /* We're nailed to this CPU. */
- src_cpu = smp_processor_id();
+ /* On same node? */
+ mask = node_to_cpumask(cpu_to_node(dead_cpu));
+ cpus_and(mask, mask, tsk->cpus_allowed);
+ dest_cpu = any_online_cpu(mask);
- /* Not required, but here for neatness. */
- write_lock(&tasklist_lock);
+ /* On any allowed CPU? */
+ if (dest_cpu == NR_CPUS)
+ dest_cpu = any_online_cpu(tsk->cpus_allowed);
- /* watch out for per node tasks, let's stay on this node */
- node = cpu_to_node(src_cpu);
+ /* No more Mr. Nice Guy. */
+ if (dest_cpu == NR_CPUS) {
+ cpus_setall(tsk->cpus_allowed);
+ dest_cpu = any_online_cpu(tsk->cpus_allowed);
+
+ /*
+ * Don't tell them about moving exiting tasks or
+ * kernel threads (both mm NULL), since they never
+ * leave kernel.
+ */
+ if (tsk->mm && printk_ratelimit())
+ printk(KERN_INFO "process %d (%s) no "
+ "longer affine to cpu%d\n",
+ tsk->pid, tsk->comm, dead_cpu);
+ }
+ __migrate_task(tsk, dead_cpu, dest_cpu);
+}
+
+/* Run through task list and migrate tasks from the dead cpu. */
+static void migrate_live_tasks(int src_cpu)
+{
+ struct task_struct *tsk, *t;
+
+ write_lock_irq(&tasklist_lock);
do_each_thread(t, tsk) {
- cpumask_t mask;
if (tsk == current)
continue;
- if (task_cpu(tsk) != src_cpu)
- continue;
+ if (task_cpu(tsk) == src_cpu)
+ move_task_off_dead_cpu(src_cpu, tsk);
+ } while_each_thread(t, tsk);
- /* Figure out where this task should go (attempting to
- * keep it on-node), and check if it can be migrated
- * as-is. NOTE that kernel threads bound to more than
- * one online cpu will be migrated. */
- mask = node_to_cpumask(node);
- cpus_and(mask, mask, tsk->cpus_allowed);
- dest_cpu = any_online_cpu(mask);
- if (dest_cpu == NR_CPUS)
- dest_cpu = any_online_cpu(tsk->cpus_allowed);
- if (dest_cpu == NR_CPUS) {
- cpus_clear(tsk->cpus_allowed);
- cpus_complement(tsk->cpus_allowed);
- dest_cpu = any_online_cpu(tsk->cpus_allowed);
-
- /* Don't tell them about moving exiting tasks
- or kernel threads (both mm NULL), since
- they never leave kernel. */
- if (tsk->mm && printk_ratelimit())
- printk(KERN_INFO "process %d (%s) no "
- "longer affine to cpu%d\n",
- tsk->pid, tsk->comm, src_cpu);
- }
+ write_unlock_irq(&tasklist_lock);
+}
- move_task_away(tsk, dest_cpu);
- } while_each_thread(t, tsk);
+/* Schedules idle task to be the next runnable task on current CPU.
+ * It does so by boosting its priority to highest possible and adding it to
+ * the _front_ of runqueue. Used by CPU offline code.
+ */
+void sched_idle_next(void)
+{
+ int cpu = smp_processor_id();
+ runqueue_t *rq = this_rq();
+ struct task_struct *p = rq->idle;
+ unsigned long flags;
+
+ /* cpu has to be offline */
+ BUG_ON(cpu_online(cpu));
+
+ /* Strictly not necessary since rest of the CPUs are stopped by now
+ * and interrupts disabled on current cpu.
+ */
+ spin_lock_irqsave(&rq->lock, flags);
- write_unlock(&tasklist_lock);
+ __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
+ /* Add idle task to _front_ of it's priority queue */
+ __activate_idle_task(p, rq);
+
+ spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static void migrate_dead(unsigned int dead_cpu, task_t *tsk)
+{
+ struct runqueue *rq = cpu_rq(dead_cpu);
+
+ /* Must be exiting, otherwise would be on tasklist. */
+ BUG_ON(tsk->state != TASK_ZOMBIE && tsk->state != TASK_DEAD);
+
+ /* Cannot have done final schedule yet: would have vanished. */
+ BUG_ON(tsk->flags & PF_DEAD);
+
+ get_task_struct(tsk);
+
+ /*
+ * Drop lock around migration; if someone else moves it,
+ * that's OK. No task can be added to this CPU, so iteration is
+ * fine.
+ */
+ spin_unlock_irq(&rq->lock);
+ move_task_off_dead_cpu(dead_cpu, tsk);
+ spin_lock_irq(&rq->lock);
+
+ put_task_struct(tsk);
+}
+
+/* release_task() removes task from tasklist, so we won't find dead tasks. */
+static void migrate_dead_tasks(unsigned int dead_cpu)
+{
+ unsigned arr, i;
+ struct runqueue *rq = cpu_rq(dead_cpu);
+
+ for (arr = 0; arr < 2; arr++) {
+ for (i = 0; i < MAX_PRIO; i++) {
+ struct list_head *list = &rq->arrays[arr].queue[i];
+ while (!list_empty(list))
+ migrate_dead(dead_cpu,
+ list_entry(list->next, task_t,
+ run_list));
+ }
+ }
}
#endif /* CONFIG_HOTPLUG_CPU */
p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
if (IS_ERR(p))
return NOTIFY_BAD;
+ p->flags |= PF_NOFREEZE;
kthread_bind(p, cpu);
/* Must be high prio: stop_machine expects to yield to it. */
rq = task_rq_lock(p, &flags);
case CPU_UP_CANCELED:
/* Unbind it from offline cpu so it can run. Fall thru. */
kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
- case CPU_DEAD:
kthread_stop(cpu_rq(cpu)->migration_thread);
cpu_rq(cpu)->migration_thread = NULL;
- BUG_ON(cpu_rq(cpu)->nr_running != 0);
- break;
+ break;
+ case CPU_DEAD:
+ migrate_live_tasks(cpu);
+ rq = cpu_rq(cpu);
+ kthread_stop(rq->migration_thread);
+ rq->migration_thread = NULL;
+ /* Idle task back to normal (off runqueue, low prio) */
+ rq = task_rq_lock(rq->idle, &flags);
+ deactivate_task(rq->idle, rq);
+ rq->idle->static_prio = MAX_PRIO;
+ __setscheduler(rq->idle, SCHED_NORMAL, 0);
+ migrate_dead_tasks(cpu);
+ task_rq_unlock(rq, &flags);
+ BUG_ON(rq->nr_running != 0);
+
+ /* No need to migrate the tasks: it was best-effort if
+ * they didn't do lock_cpu_hotplug(). Just wake up
+ * the requestors. */
+ spin_lock_irq(&rq->lock);
+ while (!list_empty(&rq->migration_queue)) {
+ migration_req_t *req;
+ req = list_entry(rq->migration_queue.next,
+ migration_req_t, list);
+ BUG_ON(req->type != REQ_MOVE_TASK);
+ list_del_init(&req->list);
+ complete(&req->done);
+ }
+ spin_unlock_irq(&rq->lock);
+ break;
#endif
}
return NOTIFY_OK;
}
+/* Register at highest priority so that task migration (migrate_all_tasks)
+ * happens before everything else.
+ */
static struct notifier_block __devinitdata migration_notifier = {
.notifier_call = migration_call,
+ .priority = 10
};
int __init migration_init(void)
spinlock_t kernel_flag __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
EXPORT_SYMBOL(kernel_flag);
+#ifdef CONFIG_SMP
+/* Attach the domain 'sd' to 'cpu' as its base domain */
+static void cpu_attach_domain(struct sched_domain *sd, int cpu)
+{
+ migration_req_t req;
+ unsigned long flags;
+ runqueue_t *rq = cpu_rq(cpu);
+ int local = 1;
+
+ lock_cpu_hotplug();
+
+ spin_lock_irqsave(&rq->lock, flags);
+
+ if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+ rq->sd = sd;
+ } else {
+ init_completion(&req.done);
+ req.type = REQ_SET_DOMAIN;
+ req.sd = sd;
+ list_add(&req.list, &rq->migration_queue);
+ local = 0;
+ }
+
+ spin_unlock_irqrestore(&rq->lock, flags);
+
+ if (!local) {
+ wake_up_process(rq->migration_thread);
+ wait_for_completion(&req.done);
+ }
+
+ unlock_cpu_hotplug();
+}
+
+/*
+ * To enable disjoint top-level NUMA domains, define SD_NODES_PER_DOMAIN
+ * in arch code. That defines the number of nearby nodes in a node's top
+ * level scheduling domain.
+ */
+#if defined(CONFIG_NUMA) && defined(SD_NODES_PER_DOMAIN)
+/**
+ * find_next_best_node - find the next node to include in a sched_domain
+ * @node: node whose sched_domain we're building
+ * @used_nodes: nodes already in the sched_domain
+ *
+ * Find the next node to include in a given scheduling domain. Simply
+ * finds the closest node not already in the @used_nodes map.
+ *
+ * Should use nodemask_t.
+ */
+static int __init find_next_best_node(int node, unsigned long *used_nodes)
+{
+ int i, n, val, min_val, best_node = 0;
+
+ min_val = INT_MAX;
+
+ for (i = 0; i < numnodes; i++) {
+ /* Start at @node */
+ n = (node + i) % numnodes;
+
+ /* Skip already used nodes */
+ if (test_bit(n, used_nodes))
+ continue;
+
+ /* Simple min distance search */
+ val = node_distance(node, i);
+
+ if (val < min_val) {
+ min_val = val;
+ best_node = n;
+ }
+ }
+
+ set_bit(best_node, used_nodes);
+ return best_node;
+}
+
+/**
+ * sched_domain_node_span - get a cpumask for a node's sched_domain
+ * @node: node whose cpumask we're constructing
+ * @size: number of nodes to include in this span
+ *
+ * Given a node, construct a good cpumask for its sched_domain to span. It
+ * should be one that prevents unnecessary balancing, but also spreads tasks
+ * out optimally.
+ */
+cpumask_t __init sched_domain_node_span(int node)
+{
+ int i;
+ cpumask_t span;
+ DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
+
+ cpus_clear(span);
+ bitmap_zero(used_nodes, MAX_NUMNODES);
+
+ for (i = 0; i < SD_NODES_PER_DOMAIN; i++) {
+ int next_node = find_next_best_node(node, used_nodes);
+ cpumask_t nodemask;
+
+ nodemask = node_to_cpumask(next_node);
+ cpus_or(span, span, nodemask);
+ }
+
+ return span;
+}
+#else /* CONFIG_NUMA && SD_NODES_PER_DOMAIN */
+cpumask_t __init sched_domain_node_span(int node)
+{
+ return cpu_possible_map;
+}
+#endif /* CONFIG_NUMA && SD_NODES_PER_DOMAIN */
+
+#ifdef CONFIG_SCHED_SMT
+static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
+static struct sched_group sched_group_cpus[NR_CPUS];
+__init static int cpu_to_cpu_group(int cpu)
+{
+ return cpu;
+}
+#endif
+
+static DEFINE_PER_CPU(struct sched_domain, phys_domains);
+static struct sched_group sched_group_phys[NR_CPUS];
+__init static int cpu_to_phys_group(int cpu)
+{
+#ifdef CONFIG_SCHED_SMT
+ return first_cpu(cpu_sibling_map[cpu]);
+#else
+ return cpu;
+#endif
+}
+
+#ifdef CONFIG_NUMA
+
+static DEFINE_PER_CPU(struct sched_domain, node_domains);
+static struct sched_group sched_group_nodes[MAX_NUMNODES];
+__init static int cpu_to_node_group(int cpu)
+{
+ return cpu_to_node(cpu);
+}
+#endif
+
+/* Groups for isolated scheduling domains */
+static struct sched_group sched_group_isolated[NR_CPUS];
+
+/* cpus with isolated domains */
+cpumask_t __initdata cpu_isolated_map = CPU_MASK_NONE;
+
+__init static int cpu_to_isolated_group(int cpu)
+{
+ return cpu;
+}
+
+/* Setup the mask of cpus configured for isolated domains */
+static int __init isolated_cpu_setup(char *str)
+{
+ int ints[NR_CPUS], i;
+
+ str = get_options(str, ARRAY_SIZE(ints), ints);
+ cpus_clear(cpu_isolated_map);
+ for (i = 1; i <= ints[0]; i++)
+ cpu_set(ints[i], cpu_isolated_map);
+ return 1;
+}
+
+__setup ("isolcpus=", isolated_cpu_setup);
+
+/*
+ * init_sched_build_groups takes an array of groups, the cpumask we wish
+ * to span, and a pointer to a function which identifies what group a CPU
+ * belongs to. The return value of group_fn must be a valid index into the
+ * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
+ * keep track of groups covered with a cpumask_t).
+ *
+ * init_sched_build_groups will build a circular linked list of the groups
+ * covered by the given span, and will set each group's ->cpumask correctly,
+ * and ->cpu_power to 0.
+ */
+__init static void init_sched_build_groups(struct sched_group groups[],
+ cpumask_t span, int (*group_fn)(int cpu))
+{
+ struct sched_group *first = NULL, *last = NULL;
+ cpumask_t covered = CPU_MASK_NONE;
+ int i;
+
+ for_each_cpu_mask(i, span) {
+ int group = group_fn(i);
+ struct sched_group *sg = &groups[group];
+ int j;
+
+ if (cpu_isset(i, covered))
+ continue;
+
+ sg->cpumask = CPU_MASK_NONE;
+ sg->cpu_power = 0;
+
+ for_each_cpu_mask(j, span) {
+ if (group_fn(j) != group)
+ continue;
+
+ cpu_set(j, covered);
+ cpu_set(j, sg->cpumask);
+ }
+ if (!first)
+ first = sg;
+ if (last)
+ last->next = sg;
+ last = sg;
+ }
+ last->next = first;
+}
+
+__init static void arch_init_sched_domains(void)
+{
+ int i;
+ cpumask_t cpu_default_map;
+
+ /*
+ * Setup mask for cpus without special case scheduling requirements.
+ * For now this just excludes isolated cpus, but could be used to
+ * exclude other special cases in the future.
+ */
+ cpus_complement(cpu_default_map, cpu_isolated_map);
+ cpus_and(cpu_default_map, cpu_default_map, cpu_possible_map);
+
+ /* Set up domains */
+ for_each_cpu(i) {
+ int group;
+ struct sched_domain *sd = NULL, *p;
+ cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
+
+ cpus_and(nodemask, nodemask, cpu_default_map);
+
+ /*
+ * Set up isolated domains.
+ * Unlike those of other cpus, the domains and groups are
+ * single level, and span a single cpu.
+ */
+ if (cpu_isset(i, cpu_isolated_map)) {
+#ifdef CONFIG_SCHED_SMT
+ sd = &per_cpu(cpu_domains, i);
+#else
+ sd = &per_cpu(phys_domains, i);
+#endif
+ group = cpu_to_isolated_group(i);
+ *sd = SD_CPU_INIT;
+ cpu_set(i, sd->span);
+ sd->balance_interval = INT_MAX; /* Don't balance */
+ sd->flags = 0; /* Avoid WAKE_ */
+ sd->groups = &sched_group_isolated[group];
+ printk(KERN_INFO "Setting up cpu %d isolated.\n", i);
+ /* Single level, so continue with next cpu */
+ continue;
+ }
+
+#ifdef CONFIG_NUMA
+ sd = &per_cpu(node_domains, i);
+ group = cpu_to_node_group(i);
+ *sd = SD_NODE_INIT;
+ /* FIXME: should be multilevel, in arch code */
+ sd->span = sched_domain_node_span(i);
+ cpus_and(sd->span, sd->span, cpu_default_map);
+ sd->groups = &sched_group_nodes[group];
+#endif
+
+ p = sd;
+ sd = &per_cpu(phys_domains, i);
+ group = cpu_to_phys_group(i);
+ *sd = SD_CPU_INIT;
+#ifdef CONFIG_NUMA
+ sd->span = nodemask;
+#else
+ sd->span = cpu_possible_map;
+#endif
+ sd->parent = p;
+ sd->groups = &sched_group_phys[group];
+
+#ifdef CONFIG_SCHED_SMT
+ p = sd;
+ sd = &per_cpu(cpu_domains, i);
+ group = cpu_to_cpu_group(i);
+ *sd = SD_SIBLING_INIT;
+ sd->span = cpu_sibling_map[i];
+ cpus_and(sd->span, sd->span, cpu_default_map);
+ sd->parent = p;
+ sd->groups = &sched_group_cpus[group];
+#endif
+ }
+
+#ifdef CONFIG_SCHED_SMT
+ /* Set up CPU (sibling) groups */
+ for_each_cpu(i) {
+ cpumask_t this_sibling_map = cpu_sibling_map[i];
+ cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
+ if (i != first_cpu(this_sibling_map))
+ continue;
+
+ init_sched_build_groups(sched_group_cpus, this_sibling_map,
+ &cpu_to_cpu_group);
+ }
+#endif
+
+ /* Set up isolated groups */
+ for_each_cpu_mask(i, cpu_isolated_map) {
+ cpumask_t mask;
+ cpus_clear(mask);
+ cpu_set(i, mask);
+ init_sched_build_groups(sched_group_isolated, mask,
+ &cpu_to_isolated_group);
+ }
+
+#ifdef CONFIG_NUMA
+ /* Set up physical groups */
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ cpumask_t nodemask = node_to_cpumask(i);
+
+ cpus_and(nodemask, nodemask, cpu_default_map);
+ if (cpus_empty(nodemask))
+ continue;
+
+ init_sched_build_groups(sched_group_phys, nodemask,
+ &cpu_to_phys_group);
+ }
+#else
+ init_sched_build_groups(sched_group_phys, cpu_possible_map,
+ &cpu_to_phys_group);
+#endif
+
+#ifdef CONFIG_NUMA
+ /* Set up node groups */
+ init_sched_build_groups(sched_group_nodes, cpu_default_map,
+ &cpu_to_node_group);
+#endif
+
+ /* Calculate CPU power for physical packages and nodes */
+ for_each_cpu_mask(i, cpu_default_map) {
+ int power;
+ struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+ sd = &per_cpu(cpu_domains, i);
+ power = SCHED_LOAD_SCALE;
+ sd->groups->cpu_power = power;
+#endif
+
+ sd = &per_cpu(phys_domains, i);
+ power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
+ (cpus_weight(sd->groups->cpumask)-1) / 10;
+ sd->groups->cpu_power = power;
+
+#ifdef CONFIG_NUMA
+ if (i == first_cpu(sd->groups->cpumask)) {
+ /* Only add "power" once for each physical package. */
+ sd = &per_cpu(node_domains, i);
+ sd->groups->cpu_power += power;
+ }
+#endif
+ }
+
+ /* Attach the domains */
+ for_each_cpu(i) {
+ struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+ sd = &per_cpu(cpu_domains, i);
+#else
+ sd = &per_cpu(phys_domains, i);
+#endif
+ cpu_attach_domain(sd, i);
+ }
+}
+
+#undef SCHED_DOMAIN_DEBUG
+#ifdef SCHED_DOMAIN_DEBUG
+void sched_domain_debug(void)
+{
+ int i;
+
+ for_each_cpu(i) {
+ runqueue_t *rq = cpu_rq(i);
+ struct sched_domain *sd;
+ int level = 0;
+
+ sd = rq->sd;
+
+ printk(KERN_DEBUG "CPU%d: %s\n",
+ i, (cpu_online(i) ? " online" : "offline"));
+
+ do {
+ int j;
+ char str[NR_CPUS];
+ struct sched_group *group = sd->groups;
+ cpumask_t groupmask;
+
+ cpumask_scnprintf(str, NR_CPUS, sd->span);
+ cpus_clear(groupmask);
+
+ printk(KERN_DEBUG);
+ for (j = 0; j < level + 1; j++)
+ printk(" ");
+ printk("domain %d: span %s\n", level, str);
+
+ if (!cpu_isset(i, sd->span))
+ printk(KERN_DEBUG "ERROR domain->span does not contain CPU%d\n", i);
+ if (!cpu_isset(i, group->cpumask))
+ printk(KERN_DEBUG "ERROR domain->groups does not contain CPU%d\n", i);
+ if (!group->cpu_power)
+ printk(KERN_DEBUG "ERROR domain->cpu_power not set\n");
+
+ printk(KERN_DEBUG);
+ for (j = 0; j < level + 2; j++)
+ printk(" ");
+ printk("groups:");
+ do {
+ if (!group) {
+ printk(" ERROR: NULL");
+ break;
+ }
+
+ if (!cpus_weight(group->cpumask))
+ printk(" ERROR empty group:");
+
+ if (cpus_intersects(groupmask, group->cpumask))
+ printk(" ERROR repeated CPUs:");
+
+ cpus_or(groupmask, groupmask, group->cpumask);
+
+ cpumask_scnprintf(str, NR_CPUS, group->cpumask);
+ printk(" %s", str);
+
+ group = group->next;
+ } while (group != sd->groups);
+ printk("\n");
+
+ if (!cpus_equal(sd->span, groupmask))
+ printk(KERN_DEBUG "ERROR groups don't span domain->span\n");
+
+ level++;
+ sd = sd->parent;
+
+ if (sd) {
+ if (!cpus_subset(groupmask, sd->span))
+ printk(KERN_DEBUG "ERROR parent span is not a superset of domain->span\n");
+ }
+
+ } while (sd);
+ }
+}
+#else
+#define sched_domain_debug() {}
+#endif
+
+void __init sched_init_smp(void)
+{
+ arch_init_sched_domains();
+ sched_domain_debug();
+}
+#else
+void __init sched_init_smp(void)
+{
+}
+#endif /* CONFIG_SMP */
+
+int in_sched_functions(unsigned long addr)
+{
+ /* Linker adds these: start and end of __sched functions */
+ extern char __sched_text_start[], __sched_text_end[];
+ return in_lock_functions(addr) ||
+ (addr >= (unsigned long)__sched_text_start
+ && addr < (unsigned long)__sched_text_end);
+}
+
void __init sched_init(void)
{
runqueue_t *rq;
int i, j, k;
+#ifdef CONFIG_SMP
+ /* Set up an initial dummy domain for early boot */
+ static struct sched_domain sched_domain_init;
+ static struct sched_group sched_group_init;
+
+ memset(&sched_domain_init, 0, sizeof(struct sched_domain));
+ sched_domain_init.span = CPU_MASK_ALL;
+ sched_domain_init.groups = &sched_group_init;
+ sched_domain_init.last_balance = jiffies;
+ sched_domain_init.balance_interval = INT_MAX; /* Don't balance */
+ sched_domain_init.busy_factor = 1;
+
+ memset(&sched_group_init, 0, sizeof(struct sched_group));
+ sched_group_init.cpumask = CPU_MASK_ALL;
+ sched_group_init.next = &sched_group_init;
+ sched_group_init.cpu_power = SCHED_LOAD_SCALE;
+#endif
+
for (i = 0; i < NR_CPUS; i++) {
prio_array_t *array;
rq = cpu_rq(i);
+ spin_lock_init(&rq->lock);
rq->active = rq->arrays;
rq->expired = rq->arrays + 1;
rq->best_expired_prio = MAX_PRIO;
- spin_lock_init(&rq->lock);
+#ifdef CONFIG_SMP
+ rq->sd = &sched_domain_init;
+ rq->cpu_load = 0;
+ rq->active_balance = 0;
+ rq->push_cpu = 0;
+ rq->migration_thread = NULL;
INIT_LIST_HEAD(&rq->migration_queue);
+#endif
+#ifdef CONFIG_VSERVER_HARDCPU
+ INIT_LIST_HEAD(&rq->hold_queue);
+#endif
atomic_set(&rq->nr_iowait, 0);
- nr_running_init(rq);
for (j = 0; j < 2; j++) {
array = rq->arrays + j;
__set_bit(MAX_PRIO, array->bitmap);
}
}
- /*
- * We have to do a little magic to get the first
- * thread right in SMP mode.
- */
- rq = this_rq();
- rq->curr = current;
- rq->idle = current;
- set_task_cpu(current, smp_processor_id());
- wake_up_forked_process(current);
-
- init_timers();
/*
* The boot idle thread does lazy MMU switching as well:
*/
atomic_inc(&init_mm.mm_count);
enter_lazy_tlb(&init_mm, current);
+
+ /*
+ * Make us the idle thread. Technically, schedule() should not be
+ * called from this thread, however somewhere below it might be,
+ * but because we are the idle thread, we just pick up running again
+ * when this runqueue becomes "idle".
+ */
+ init_idle(current, smp_processor_id());
}
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
}
EXPORT_SYMBOL(__might_sleep);
#endif
-
-
-#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
-/*
- * This could be a long-held lock. If another CPU holds it for a long time,
- * and that CPU is not asked to reschedule then *this* CPU will spin on the
- * lock for a long time, even if *this* CPU is asked to reschedule.
- *
- * So what we do here, in the slow (contended) path is to spin on the lock by
- * hand while permitting preemption.
- *
- * Called inside preempt_disable().
- */
-void __sched __preempt_spin_lock(spinlock_t *lock)
-{
- if (preempt_count() > 1) {
- _raw_spin_lock(lock);
- return;
- }
- do {
- preempt_enable();
- while (spin_is_locked(lock))
- cpu_relax();
- preempt_disable();
- } while (!_raw_spin_trylock(lock));
-}
-
-EXPORT_SYMBOL(__preempt_spin_lock);
-
-void __sched __preempt_write_lock(rwlock_t *lock)
-{
- if (preempt_count() > 1) {
- _raw_write_lock(lock);
- return;
- }
-
- do {
- preempt_enable();
- while (rwlock_is_locked(lock))
- cpu_relax();
- preempt_disable();
- } while (!_raw_write_trylock(lock));
-}
-
-EXPORT_SYMBOL(__preempt_write_lock);
-#endif /* defined(CONFIG_SMP) && defined(CONFIG_PREEMPT) */
git://git.onelab.eu / linux-2.6.git / blobdiff