/*
* linux/kernel/profile.c
- * Simple profiling. Manages a direct-mapped profile hit count buffer,
- * with configurable resolution, support for restricting the cpus on
- * which profiling is done, and switching between cpu time and
- * schedule() calls via kernel command line parameters passed at boot.
- *
- * Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
- * Red Hat, July 2004
- * Consolidation of architecture support code for profiling,
- * William Irwin, Oracle, July 2004
- * Amortized hit count accounting via per-cpu open-addressed hashtables
- * to resolve timer interrupt livelocks, William Irwin, Oracle, 2004
*/
#include <linux/config.h>
#include <linux/notifier.h>
#include <linux/mm.h>
#include <linux/cpumask.h>
-#include <linux/cpu.h>
#include <linux/profile.h>
-#include <linux/highmem.h>
#include <asm/sections.h>
-#include <asm/semaphore.h>
-
-struct profile_hit {
- u32 pc, hits;
-};
-#define PROFILE_GRPSHIFT 3
-#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
-#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
-#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
-
-/* Oprofile timer tick hook */
-int (*timer_hook)(struct pt_regs *);
static atomic_t *prof_buffer;
static unsigned long prof_len, prof_shift;
static int prof_on;
static cpumask_t prof_cpu_mask = CPU_MASK_ALL;
-#ifdef CONFIG_SMP
-static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
-static DEFINE_PER_CPU(int, cpu_profile_flip);
-static DECLARE_MUTEX(profile_flip_mutex);
-#endif /* CONFIG_SMP */
static int __init profile_setup(char * str)
{
int par;
if (!strncmp(str, "schedule", 8)) {
- prof_on = SCHED_PROFILING;
+ prof_on = 2;
printk(KERN_INFO "kernel schedule profiling enabled\n");
if (str[7] == ',')
str += 8;
}
if (get_option(&str,&par)) {
prof_shift = par;
- prof_on = CPU_PROFILING;
+ prof_on = 1;
printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
prof_shift);
}
return err;
}
-int register_timer_hook(int (*hook)(struct pt_regs *))
-{
- if (timer_hook)
- return -EBUSY;
- timer_hook = hook;
- return 0;
-}
-
-void unregister_timer_hook(int (*hook)(struct pt_regs *))
+static struct notifier_block * profile_listeners;
+static rwlock_t profile_lock = RW_LOCK_UNLOCKED;
+
+int register_profile_notifier(struct notifier_block * nb)
{
- WARN_ON(hook != timer_hook);
- timer_hook = NULL;
- /* make sure all CPUs see the NULL hook */
- synchronize_kernel();
+ int err;
+ write_lock_irq(&profile_lock);
+ err = notifier_chain_register(&profile_listeners, nb);
+ write_unlock_irq(&profile_lock);
+ return err;
}
-EXPORT_SYMBOL_GPL(register_timer_hook);
-EXPORT_SYMBOL_GPL(unregister_timer_hook);
-EXPORT_SYMBOL_GPL(task_handoff_register);
-EXPORT_SYMBOL_GPL(task_handoff_unregister);
-
-#endif /* CONFIG_PROFILING */
-EXPORT_SYMBOL_GPL(profile_event_register);
-EXPORT_SYMBOL_GPL(profile_event_unregister);
-
-#ifdef CONFIG_SMP
-/*
- * Each cpu has a pair of open-addressed hashtables for pending
- * profile hits. read_profile() IPI's all cpus to request them
- * to flip buffers and flushes their contents to prof_buffer itself.
- * Flip requests are serialized by the profile_flip_mutex. The sole
- * use of having a second hashtable is for avoiding cacheline
- * contention that would otherwise happen during flushes of pending
- * profile hits required for the accuracy of reported profile hits
- * and so resurrect the interrupt livelock issue.
- *
- * The open-addressed hashtables are indexed by profile buffer slot
- * and hold the number of pending hits to that profile buffer slot on
- * a cpu in an entry. When the hashtable overflows, all pending hits
- * are accounted to their corresponding profile buffer slots with
- * atomic_add() and the hashtable emptied. As numerous pending hits
- * may be accounted to a profile buffer slot in a hashtable entry,
- * this amortizes a number of atomic profile buffer increments likely
- * to be far larger than the number of entries in the hashtable,
- * particularly given that the number of distinct profile buffer
- * positions to which hits are accounted during short intervals (e.g.
- * several seconds) is usually very small. Exclusion from buffer
- * flipping is provided by interrupt disablement (note that for
- * SCHED_PROFILING profile_hit() may be called from process context).
- * The hash function is meant to be lightweight as opposed to strong,
- * and was vaguely inspired by ppc64 firmware-supported inverted
- * pagetable hash functions, but uses a full hashtable full of finite
- * collision chains, not just pairs of them.
- *
- * -- wli
- */
-static void __profile_flip_buffers(void *unused)
+int unregister_profile_notifier(struct notifier_block * nb)
{
- int cpu = smp_processor_id();
-
- per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
+ int err;
+ write_lock_irq(&profile_lock);
+ err = notifier_chain_unregister(&profile_listeners, nb);
+ write_unlock_irq(&profile_lock);
+ return err;
}
-static void profile_flip_buffers(void)
-{
- int i, j, cpu;
-
- down(&profile_flip_mutex);
- j = per_cpu(cpu_profile_flip, get_cpu());
- put_cpu();
- on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
- for_each_online_cpu(cpu) {
- struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
- for (i = 0; i < NR_PROFILE_HIT; ++i) {
- if (!hits[i].hits) {
- if (hits[i].pc)
- hits[i].pc = 0;
- continue;
- }
- atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
- hits[i].hits = hits[i].pc = 0;
- }
- }
- up(&profile_flip_mutex);
-}
-static void profile_discard_flip_buffers(void)
+void profile_hook(struct pt_regs * regs)
{
- int i, cpu;
-
- down(&profile_flip_mutex);
- i = per_cpu(cpu_profile_flip, get_cpu());
- put_cpu();
- on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
- for_each_online_cpu(cpu) {
- struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
- memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
- }
- up(&profile_flip_mutex);
+ read_lock(&profile_lock);
+ notifier_call_chain(&profile_listeners, 0, regs);
+ read_unlock(&profile_lock);
}
-void profile_hit(int type, void *__pc)
-{
- unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
- int i, j, cpu;
- struct profile_hit *hits;
+EXPORT_SYMBOL_GPL(register_profile_notifier);
+EXPORT_SYMBOL_GPL(unregister_profile_notifier);
+EXPORT_SYMBOL_GPL(task_handoff_register);
+EXPORT_SYMBOL_GPL(task_handoff_unregister);
- if (prof_on != type || !prof_buffer)
- return;
- pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
- i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
- secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
- cpu = get_cpu();
- hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
- if (!hits) {
- put_cpu();
- return;
- }
- local_irq_save(flags);
- do {
- for (j = 0; j < PROFILE_GRPSZ; ++j) {
- if (hits[i + j].pc == pc) {
- hits[i + j].hits++;
- goto out;
- } else if (!hits[i + j].hits) {
- hits[i + j].pc = pc;
- hits[i + j].hits = 1;
- goto out;
- }
- }
- i = (i + secondary) & (NR_PROFILE_HIT - 1);
- } while (i != primary);
- atomic_inc(&prof_buffer[pc]);
- for (i = 0; i < NR_PROFILE_HIT; ++i) {
- atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
- hits[i].pc = hits[i].hits = 0;
- }
-out:
- local_irq_restore(flags);
- put_cpu();
-}
+#endif /* CONFIG_PROFILING */
-#ifdef CONFIG_HOTPLUG_CPU
-static int __devinit profile_cpu_callback(struct notifier_block *info,
- unsigned long action, void *__cpu)
-{
- int node, cpu = (unsigned long)__cpu;
- struct page *page;
-
- switch (action) {
- case CPU_UP_PREPARE:
- node = cpu_to_node(cpu);
- per_cpu(cpu_profile_flip, cpu) = 0;
- if (!per_cpu(cpu_profile_hits, cpu)[1]) {
- page = alloc_pages_node(node, GFP_KERNEL, 0);
- if (!page)
- return NOTIFY_BAD;
- clear_highpage(page);
- per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
- }
- if (!per_cpu(cpu_profile_hits, cpu)[0]) {
- page = alloc_pages_node(node, GFP_KERNEL, 0);
- if (!page)
- goto out_free;
- clear_highpage(page);
- per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
- }
- break;
- out_free:
- page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
- per_cpu(cpu_profile_hits, cpu)[1] = NULL;
- __free_page(page);
- return NOTIFY_BAD;
- case CPU_ONLINE:
- cpu_set(cpu, prof_cpu_mask);
- break;
- case CPU_UP_CANCELED:
- case CPU_DEAD:
- cpu_clear(cpu, prof_cpu_mask);
- if (per_cpu(cpu_profile_hits, cpu)[0]) {
- page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
- per_cpu(cpu_profile_hits, cpu)[0] = NULL;
- __free_page(page);
- }
- if (per_cpu(cpu_profile_hits, cpu)[1]) {
- page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
- per_cpu(cpu_profile_hits, cpu)[1] = NULL;
- __free_page(page);
- }
- break;
- }
- return NOTIFY_OK;
-}
-#endif /* CONFIG_HOTPLUG_CPU */
-#else /* !CONFIG_SMP */
-#define profile_flip_buffers() do { } while (0)
-#define profile_discard_flip_buffers() do { } while (0)
+EXPORT_SYMBOL_GPL(profile_event_register);
+EXPORT_SYMBOL_GPL(profile_event_unregister);
void profile_hit(int type, void *__pc)
{
pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);
}
-#endif /* !CONFIG_SMP */
void profile_tick(int type, struct pt_regs *regs)
{
- if (type == CPU_PROFILING && timer_hook)
- timer_hook(regs);
+ if (type == CPU_PROFILING)
+ profile_hook(regs);
if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
profile_hit(type, (void *)profile_pc(regs));
}
char * pnt;
unsigned int sample_step = 1 << prof_shift;
- profile_flip_buffers();
if (p >= (prof_len+1)*sizeof(unsigned int))
return 0;
if (count > (prof_len+1)*sizeof(unsigned int) - p)
return -EINVAL;
}
#endif
- profile_discard_flip_buffers();
+
memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
return count;
}
.write = write_profile,
};
-#ifdef CONFIG_SMP
-static void __init profile_nop(void *unused)
-{
-}
-
-static int __init create_hash_tables(void)
-{
- int cpu;
-
- for_each_online_cpu(cpu) {
- int node = cpu_to_node(cpu);
- struct page *page;
-
- page = alloc_pages_node(node, GFP_KERNEL, 0);
- if (!page)
- goto out_cleanup;
- clear_highpage(page);
- per_cpu(cpu_profile_hits, cpu)[1]
- = (struct profile_hit *)page_address(page);
- page = alloc_pages_node(node, GFP_KERNEL, 0);
- if (!page)
- goto out_cleanup;
- clear_highpage(page);
- per_cpu(cpu_profile_hits, cpu)[0]
- = (struct profile_hit *)page_address(page);
- }
- return 0;
-out_cleanup:
- prof_on = 0;
- mb();
- on_each_cpu(profile_nop, NULL, 0, 1);
- for_each_online_cpu(cpu) {
- struct page *page;
-
- if (per_cpu(cpu_profile_hits, cpu)[0]) {
- page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
- per_cpu(cpu_profile_hits, cpu)[0] = NULL;
- __free_page(page);
- }
- if (per_cpu(cpu_profile_hits, cpu)[1]) {
- page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
- per_cpu(cpu_profile_hits, cpu)[1] = NULL;
- __free_page(page);
- }
- }
- return -1;
-}
-#else
-#define create_hash_tables() ({ 0; })
-#endif
-
static int __init create_proc_profile(void)
{
struct proc_dir_entry *entry;
if (!prof_on)
return 0;
- if (create_hash_tables())
- return -1;
if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL)))
return 0;
entry->proc_fops = &proc_profile_operations;
entry->size = (1+prof_len) * sizeof(atomic_t);
- hotcpu_notifier(profile_cpu_callback, 0);
return 0;
}
module_init(create_proc_profile);
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