Commit 0338c9d7 authored Mar 17, 2017 by Dietmar Eggemann Committed by Chris Redpath Dec 19, 2017

ANDROID: sched/events: Introduce task_group load tracking trace event



The trace event key load is mapped to:

 (1) load : cfs_rq->tg->load_avg

The cfs_rq owned by the task_group is used as the only parameter for the
trace event because it has a reference to the taskgroup and the cpu.
Using the taskgroup as a parameter instead would require the cpu as a
second parameter. A task_group is global and not per-cpu data. The cpu
key only tells on which cpu the value was gathered.

The following list shows examples of the key=value pairs for:

 (1) a task group:

     cpu=1 path=/tg1/tg11/tg111 load=517

 (2) an autogroup:

     cpu=1 path=/autogroup-10 load=1050

We don't maintain a load signal for a root task group.

The trace event is only defined if cfs group scheduling support
(CONFIG_FAIR_GROUP_SCHED) is enabled.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Change-Id: I945bd1a5bbc71f215891ecfe3750a6b997102dc8
Signed-off-by: Chris Redpath <chris.redpath@arm.com>

parent acfe25da

include/trace/events/sched.h

+29 −0

Original line number	Diff line number	Diff line
		@@ -679,6 +679,35 @@ TRACE_EVENT(sched_load_se,
		__entry->cpu, __get_str(path), __entry->comm,
		__entry->pid, __entry->load, __entry->util)
		);

		/*
		* Tracepoint for task_group load tracking:
		*/
		#ifdef CONFIG_FAIR_GROUP_SCHED
		TRACE_EVENT(sched_load_tg,

		TP_PROTO(struct cfs_rq *cfs_rq),

		TP_ARGS(cfs_rq),

		TP_STRUCT__entry(
		__field( int, cpu )
		__dynamic_array(char, path,
		__trace_sched_path(cfs_rq, NULL, 0) )
		__field( long, load )
		),

		TP_fast_assign(
		__entry->cpu = cfs_rq->rq->cpu;
		__trace_sched_path(cfs_rq, __get_dynamic_array(path),
		__get_dynamic_array_len(path));
		__entry->load = atomic_long_read(&cfs_rq->tg->load_avg);
		),

		TP_printk("cpu=%d path=%s load=%ld", __entry->cpu, __get_str(path),
		__entry->load)
		);
		#endif /* CONFIG_FAIR_GROUP_SCHED */
		#endif /* CONFIG_SMP */
		#endif /* _TRACE_SCHED_H */

kernel/sched/fair.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -3103,6 +3103,8 @@ static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
		atomic_long_add(delta, &cfs_rq->tg->load_avg);
		cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
		}

		trace_sched_load_tg(cfs_rq);
		}

		/*