Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 57e7986e authored by Paul Mackerras's avatar Paul Mackerras Committed by Ingo Molnar
Browse files

perf_counter: Provide a way to enable counters on exec 



This provides a way to mark a counter to be enabled on the next
exec. This is useful for measuring the total activity of a
program without including overhead from the process that
launches it.

This also changes the perf stat command to use this new
facility.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <19017.43927.838745.689203@cargo.ozlabs.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 051ae7f7

include/linux/perf_counter.h

+2 −1
Original line number Diff line number Diff line
@@ -179,8 +179,9 @@ struct perf_counter_attr { 
				comm	       :  1, /* include comm data     */

				freq           :  1, /* use freq, not period  */

				inherit_stat   :  1, /* per task counts       */

				enable_on_exec :  1, /* next exec enables     */



				__reserved_1   : 52;

				__reserved_1   : 51;



	__u32			wakeup_events;	/* wakeup every n events */

	__u32			__reserved_2;

kernel/perf_counter.c

+50 −0
Original line number Diff line number Diff line
@@ -1428,6 +1428,53 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu) 
		perf_counter_task_sched_in(curr, cpu);

}



/*

 * Enable all of a task's counters that have been marked enable-on-exec.

 * This expects task == current.

 */

static void perf_counter_enable_on_exec(struct task_struct *task)

{

	struct perf_counter_context *ctx;

	struct perf_counter *counter;

	unsigned long flags;

	int enabled = 0;



	local_irq_save(flags);

	ctx = task->perf_counter_ctxp;

	if (!ctx || !ctx->nr_counters)

		goto out;



	__perf_counter_task_sched_out(ctx);



	spin_lock(&ctx->lock);



	list_for_each_entry(counter, &ctx->counter_list, list_entry) {

		if (!counter->attr.enable_on_exec)

			continue;

		counter->attr.enable_on_exec = 0;

		if (counter->state >= PERF_COUNTER_STATE_INACTIVE)

			continue;

		counter->state = PERF_COUNTER_STATE_INACTIVE;

		counter->tstamp_enabled =

			ctx->time - counter->total_time_enabled;

		enabled = 1;

	}



	/*

	 * Unclone this context if we enabled any counter.

	 */

	if (enabled && ctx->parent_ctx) {

		put_ctx(ctx->parent_ctx);

		ctx->parent_ctx = NULL;

	}



	spin_unlock(&ctx->lock);



	perf_counter_task_sched_in(task, smp_processor_id());

 out:

	local_irq_restore(flags);

}



/*

 * Cross CPU call to read the hardware counter

 */
@@ -2949,6 +2996,9 @@ void perf_counter_comm(struct task_struct *task) 
{

	struct perf_comm_event comm_event;



	if (task->perf_counter_ctxp)

		perf_counter_enable_on_exec(task);



	if (!atomic_read(&nr_comm_counters))

		return;

tools/perf/builtin-stat.c

+3 −3
Original line number Diff line number Diff line
@@ -118,6 +118,7 @@ static void create_perf_stat_counter(int counter, int pid) 
	} else {

		attr->inherit	     = inherit;

		attr->disabled	     = 1;

		attr->enable_on_exec = 1;



		fd[0][counter] = sys_perf_counter_open(attr, pid, -1, -1, 0);

		if (fd[0][counter] < 0 && verbose)
@@ -262,7 +263,6 @@ static int run_perf_stat(int argc, const char **argv) 
	 * Enable counters and exec the command:

	 */

	t0 = rdclock();

	prctl(PR_TASK_PERF_COUNTERS_ENABLE);



	close(go_pipe[1]);

	wait(&status);