X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=drivers%2Foprofile%2Fcpu_buffer.c;h=e9b1772a3a28cdfb7253faac3f2d24447946dd4a;hb=f7f1b0f1e2fbadeab12d24236000e778aa9b1ead;hp=23979d38dde761a048ab52e38dcd5e628b94aa7e;hpb=5273a3df6485dc2ad6aa7ddd441b9a21970f003b;p=linux-2.6.git diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c index 23979d38d..e9b1772a3 100644 --- a/drivers/oprofile/cpu_buffer.c +++ b/drivers/oprofile/cpu_buffer.c @@ -9,7 +9,7 @@ * Each CPU has a local buffer that stores PC value/event * pairs. We also log context switches when we notice them. * Eventually each CPU's buffer is processed into the global - * event buffer by sync_cpu_buffers(). + * event buffer by sync_buffer(). * * We use a local buffer for two reasons: an NMI or similar * interrupt cannot synchronise, and high sampling rates @@ -18,25 +18,28 @@ */ #include +#include #include #include +#include "event_buffer.h" #include "cpu_buffer.h" +#include "buffer_sync.h" #include "oprof.h" struct oprofile_cpu_buffer cpu_buffer[NR_CPUS] __cacheline_aligned; -static void __free_cpu_buffers(int num) +static void wq_sync_buffer(void *); + +#define DEFAULT_TIMER_EXPIRE (HZ / 10) +static int work_enabled; + +void free_cpu_buffers(void) { int i; - for (i=0; i < num; ++i) { - struct oprofile_cpu_buffer * b = &cpu_buffer[i]; - - if (!cpu_possible(i)) - continue; - - vfree(b->buffer); + for_each_online_cpu(i) { + vfree(cpu_buffer[i].buffer); } } @@ -47,35 +50,75 @@ int alloc_cpu_buffers(void) unsigned long buffer_size = fs_cpu_buffer_size; - for (i=0; i < NR_CPUS; ++i) { + for_each_online_cpu(i) { struct oprofile_cpu_buffer * b = &cpu_buffer[i]; - if (!cpu_possible(i)) - continue; - b->buffer = vmalloc(sizeof(struct op_sample) * buffer_size); if (!b->buffer) goto fail; - b->last_task = 0; + b->last_task = NULL; b->last_is_kernel = -1; + b->tracing = 0; b->buffer_size = buffer_size; b->tail_pos = 0; b->head_pos = 0; b->sample_received = 0; b->sample_lost_overflow = 0; - b->sample_lost_task_exit = 0; + b->cpu = i; + INIT_WORK(&b->work, wq_sync_buffer, b); } return 0; + fail: - __free_cpu_buffers(i); + free_cpu_buffers(); return -ENOMEM; } -void free_cpu_buffers(void) +void start_cpu_work(void) { - __free_cpu_buffers(NR_CPUS); + int i; + + work_enabled = 1; + + for_each_online_cpu(i) { + struct oprofile_cpu_buffer * b = &cpu_buffer[i]; + + /* + * Spread the work by 1 jiffy per cpu so they dont all + * fire at once. + */ + schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i); + } +} + + +void end_cpu_work(void) +{ + int i; + + work_enabled = 0; + + for_each_online_cpu(i) { + struct oprofile_cpu_buffer * b = &cpu_buffer[i]; + + cancel_delayed_work(&b->work); + } + + flush_scheduled_work(); +} + + +/* Resets the cpu buffer to a sane state. */ +void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf) +{ + /* reset these to invalid values; the next sample + * collected will populate the buffer with proper + * values to initialize the buffer + */ + cpu_buf->last_is_kernel = -1; + cpu_buf->last_task = NULL; } @@ -100,81 +143,165 @@ static void increment_head(struct oprofile_cpu_buffer * b) * increment is visible */ wmb(); - if (new_head < (b->buffer_size)) + if (new_head < b->buffer_size) b->head_pos = new_head; else b->head_pos = 0; } + + +inline static void +add_sample(struct oprofile_cpu_buffer * cpu_buf, + unsigned long pc, unsigned long event) +{ + struct op_sample * entry = &cpu_buf->buffer[cpu_buf->head_pos]; + entry->eip = pc; + entry->event = event; + increment_head(cpu_buf); +} + + +inline static void +add_code(struct oprofile_cpu_buffer * buffer, unsigned long value) +{ + add_sample(buffer, ESCAPE_CODE, value); +} + + /* This must be safe from any context. It's safe writing here * because of the head/tail separation of the writer and reader * of the CPU buffer. * * is_kernel is needed because on some architectures you cannot * tell if you are in kernel or user space simply by looking at - * eip. We tag this in the buffer by generating kernel enter/exit + * pc. We tag this in the buffer by generating kernel enter/exit * events whenever is_kernel changes */ -void oprofile_add_sample(unsigned long eip, unsigned int is_kernel, - unsigned long event, int cpu) +static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc, + int is_kernel, unsigned long event) { - struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[cpu]; struct task_struct * task; - is_kernel = !!is_kernel; - cpu_buf->sample_received++; - if (nr_available_slots(cpu_buf) < 3) { cpu_buf->sample_lost_overflow++; - return; + return 0; } + is_kernel = !!is_kernel; + task = current; /* notice a switch from user->kernel or vice versa */ if (cpu_buf->last_is_kernel != is_kernel) { cpu_buf->last_is_kernel = is_kernel; - cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL; - cpu_buf->buffer[cpu_buf->head_pos].event = is_kernel; - increment_head(cpu_buf); + add_code(cpu_buf, is_kernel); } /* notice a task switch */ if (cpu_buf->last_task != task) { cpu_buf->last_task = task; - if (!(task->flags & PF_EXITING)) { - cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL; - cpu_buf->buffer[cpu_buf->head_pos].event = (unsigned long)task; - increment_head(cpu_buf); - } + add_code(cpu_buf, (unsigned long)task); } - /* If the task is exiting it's not safe to take a sample - * as the task_struct is about to be freed. We can't just - * notify at release_task() time because of CLONE_DETACHED - * tasks that release_task() themselves. - */ - if (task->flags & PF_EXITING) { - cpu_buf->sample_lost_task_exit++; + add_sample(cpu_buf, pc, event); + return 1; +} + +static int oprofile_begin_trace(struct oprofile_cpu_buffer * cpu_buf) +{ + if (nr_available_slots(cpu_buf) < 4) { + cpu_buf->sample_lost_overflow++; + return 0; + } + + add_code(cpu_buf, CPU_TRACE_BEGIN); + cpu_buf->tracing = 1; + return 1; +} + + +static void oprofile_end_trace(struct oprofile_cpu_buffer * cpu_buf) +{ + cpu_buf->tracing = 0; +} + + +void oprofile_add_sample(struct pt_regs * const regs, unsigned long event) +{ + struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()]; + unsigned long pc = profile_pc(regs); + int is_kernel = !user_mode(regs); + + if (!backtrace_depth) { + log_sample(cpu_buf, pc, is_kernel, event); return; } - - cpu_buf->buffer[cpu_buf->head_pos].eip = eip; - cpu_buf->buffer[cpu_buf->head_pos].event = event; - increment_head(cpu_buf); + + if (!oprofile_begin_trace(cpu_buf)) + return; + + /* if log_sample() fail we can't backtrace since we lost the source + * of this event */ + if (log_sample(cpu_buf, pc, is_kernel, event)) + oprofile_ops.backtrace(regs, backtrace_depth); + oprofile_end_trace(cpu_buf); } -/* Resets the cpu buffer to a sane state. */ -void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf) +void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event) { - /* reset these to invalid values; the next sample - * collected will populate the buffer with proper - * values to initialize the buffer - */ - cpu_buf->last_is_kernel = -1; - cpu_buf->last_task = 0; + struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()]; + log_sample(cpu_buf, pc, is_kernel, event); +} + + +void oprofile_add_trace(unsigned long pc) +{ + struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()]; + + if (!cpu_buf->tracing) + return; + + if (nr_available_slots(cpu_buf) < 1) { + cpu_buf->tracing = 0; + cpu_buf->sample_lost_overflow++; + return; + } + + /* broken frame can give an eip with the same value as an escape code, + * abort the trace if we get it */ + if (pc == ESCAPE_CODE) { + cpu_buf->tracing = 0; + cpu_buf->backtrace_aborted++; + return; + } + + add_sample(cpu_buf, pc, 0); +} + + + +/* + * This serves to avoid cpu buffer overflow, and makes sure + * the task mortuary progresses + * + * By using schedule_delayed_work_on and then schedule_delayed_work + * we guarantee this will stay on the correct cpu + */ +static void wq_sync_buffer(void * data) +{ + struct oprofile_cpu_buffer * b = data; + if (b->cpu != smp_processor_id()) { + printk("WQ on CPU%d, prefer CPU%d\n", + smp_processor_id(), b->cpu); + } + sync_buffer(b->cpu); + + /* don't re-add the work if we're shutting down */ + if (work_enabled) + schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE); }