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Commit 699b5b92 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
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perf sched timehist: Save callchain when entering idle 



In order to investigate the idleness reason, it is necessary to keep the
callchains when entering idle.  This can be identified by the
sched:sched_switch event having the next_pid field as 0.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarDavid Ahern <dsahern@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161208144755.16673-4-namhyung@kernel.org
Link: http://lkml.kernel.org/r/20161213080632.19099-1-namhyung@kernel.org


[ Merged fix from Namhyung, see second Link: tag ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 3bc2fa9c

tools/perf/builtin-sched.c

+30 −0
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ struct perf_sched { 
	/* options for timehist command */

	bool		summary;

	bool		summary_only;

	bool		idle_hist;

	bool		show_callchain;

	unsigned int	max_stack;

	bool		show_cpu_visual;
@@ -2101,6 +2102,15 @@ static struct thread *get_idle_thread(int cpu) 
	return idle_threads[cpu];

}



static void save_idle_callchain(struct idle_thread_runtime *itr,

				struct perf_sample *sample)

{

	if (!symbol_conf.use_callchain || sample->callchain == NULL)

		return;



	callchain_cursor__copy(&itr->cursor, &callchain_cursor);

}



/*

 * handle runtime stats saved per thread

 */
@@ -2154,6 +2164,26 @@ static struct thread *timehist_get_thread(struct perf_sched *sched, 
		}



		save_task_callchain(sched, sample, evsel, machine);

		if (sched->idle_hist) {

			struct thread *idle;

			struct idle_thread_runtime *itr;



			idle = get_idle_thread(sample->cpu);

			if (idle == NULL) {

				pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);

				return NULL;

			}



			itr = thread__priv(idle);

			if (itr == NULL)

				return NULL;



			itr->last_thread = thread;



			/* copy task callchain when entering to idle */

			if (perf_evsel__intval(evsel, sample, "next_pid") == 0)

				save_idle_callchain(itr, sample);

		}

	}



	return thread;