From 38b200d67636a30cb8dc1508137908e7a649b5c9 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 23 Jun 2009 20:13:11 +0200 Subject: perf_counter: Add PERF_EVENT_READ Provide a read() like event which can be used to log the counter value at specific sites such as child->parent folding on exit. In order to be useful, we log the counter parent ID, not the actual counter ID, since userspace can only relate parent IDs to perf_counter_attr constructs. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- include/linux/perf_counter.h | 12 ++++++++ kernel/perf_counter.c | 72 +++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 80 insertions(+), 4 deletions(-) diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index bcbf1c4..6a384f0 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -335,6 +335,18 @@ enum perf_event_type { PERF_EVENT_FORK = 7, /* + * struct { + * struct perf_event_header header; + * u32 pid, tid; + * u64 value; + * { u64 time_enabled; } && PERF_FORMAT_ENABLED + * { u64 time_running; } && PERF_FORMAT_RUNNING + * { u64 parent_id; } && PERF_FORMAT_ID + * }; + */ + PERF_EVENT_READ = 8, + + /* * When header.misc & PERF_EVENT_MISC_OVERFLOW the event_type field * will be PERF_SAMPLE_* * diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 02994a7..a72c20e 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -2624,6 +2624,66 @@ static void perf_counter_output(struct perf_counter *counter, int nmi, } /* + * read event + */ + +struct perf_read_event { + struct perf_event_header header; + + u32 pid; + u32 tid; + u64 value; + u64 format[3]; +}; + +static void +perf_counter_read_event(struct perf_counter *counter, + struct task_struct *task) +{ + struct perf_output_handle handle; + struct perf_read_event event = { + .header = { + .type = PERF_EVENT_READ, + .misc = 0, + .size = sizeof(event) - sizeof(event.format), + }, + .pid = perf_counter_pid(counter, task), + .tid = perf_counter_tid(counter, task), + .value = atomic64_read(&counter->count), + }; + int ret, i = 0; + + if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) { + event.header.size += sizeof(u64); + event.format[i++] = counter->total_time_enabled; + } + + if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) { + event.header.size += sizeof(u64); + event.format[i++] = counter->total_time_running; + } + + if (counter->attr.read_format & PERF_FORMAT_ID) { + u64 id; + + event.header.size += sizeof(u64); + if (counter->parent) + id = counter->parent->id; + else + id = counter->id; + + event.format[i++] = id; + } + + ret = perf_output_begin(&handle, counter, event.header.size, 0, 0); + if (ret) + return; + + perf_output_copy(&handle, &event, event.header.size); + perf_output_end(&handle); +} + +/* * fork tracking */ @@ -3985,10 +4045,13 @@ static int inherit_group(struct perf_counter *parent_counter, } static void sync_child_counter(struct perf_counter *child_counter, - struct perf_counter *parent_counter) + struct task_struct *child) { + struct perf_counter *parent_counter = child_counter->parent; u64 child_val; + perf_counter_read_event(child_counter, child); + child_val = atomic64_read(&child_counter->count); /* @@ -4017,7 +4080,8 @@ static void sync_child_counter(struct perf_counter *child_counter, static void __perf_counter_exit_task(struct perf_counter *child_counter, - struct perf_counter_context *child_ctx) + struct perf_counter_context *child_ctx, + struct task_struct *child) { struct perf_counter *parent_counter; @@ -4031,7 +4095,7 @@ __perf_counter_exit_task(struct perf_counter *child_counter, * counters need to be zapped - but otherwise linger. */ if (parent_counter) { - sync_child_counter(child_counter, parent_counter); + sync_child_counter(child_counter, child); free_counter(child_counter); } } @@ -4093,7 +4157,7 @@ void perf_counter_exit_task(struct task_struct *child) again: list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list, list_entry) - __perf_counter_exit_task(child_counter, child_ctx); + __perf_counter_exit_task(child_counter, child_ctx, child); /* * If the last counter was a group counter, it will have appended all -- cgit v1.1