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Commit e06c61a8 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perfcounters: add nr-of-faults counter 



Impact: add new feature, new sw counter

Add a counter that counts the number of pagefaults a task
is experiencing.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6c594c21

kernel/perf_counter.c

+51 −0
Original line number Diff line number Diff line
@@ -888,6 +888,54 @@ static const struct hw_perf_counter_ops perf_ops_task_clock = { 
	.hw_perf_counter_read		= task_clock_perf_counter_read,

};



static u64 get_page_faults(void)

{

	struct task_struct *curr = current;



	return curr->maj_flt + curr->min_flt;

}



static void page_faults_perf_counter_update(struct perf_counter *counter)

{

	u64 prev, now;

	s64 delta;



	prev = atomic64_read(&counter->hw.prev_count);

	now = get_page_faults();



	atomic64_set(&counter->hw.prev_count, now);



	delta = now - prev;

	if (WARN_ON_ONCE(delta < 0))

		delta = 0;



	atomic64_add(delta, &counter->count);

}



static void page_faults_perf_counter_read(struct perf_counter *counter)

{

	page_faults_perf_counter_update(counter);

}



static void page_faults_perf_counter_enable(struct perf_counter *counter)

{

	/*

	 * page-faults is a per-task value already,

	 * so we dont have to clear it on switch-in.

	 */

}



static void page_faults_perf_counter_disable(struct perf_counter *counter)

{

	page_faults_perf_counter_update(counter);

}



static const struct hw_perf_counter_ops perf_ops_page_faults = {

	.hw_perf_counter_enable		= page_faults_perf_counter_enable,

	.hw_perf_counter_disable	= page_faults_perf_counter_disable,

	.hw_perf_counter_read		= page_faults_perf_counter_read,

};



static u64 get_context_switches(void)

{

	struct task_struct *curr = current;
@@ -994,6 +1042,9 @@ sw_perf_counter_init(struct perf_counter *counter) 
	case PERF_COUNT_TASK_CLOCK:

		hw_ops = &perf_ops_task_clock;

		break;

	case PERF_COUNT_PAGE_FAULTS:

		hw_ops = &perf_ops_page_faults;

		break;

	case PERF_COUNT_CONTEXT_SWITCHES:

		hw_ops = &perf_ops_context_switches;

		break;