sched/debug: Add sched_overutilized tracepoint (f9f240f9) · Commits · 戴 / test

The new tracepoint allows us to track the changes in overutilized status. Overutilized status is associated with EAS. It indicates that the system is in high performance state. EAS is disabled when the system is in this state since there's not much energy savings while high performance tasks are pushing the system to the limit and it's better to default to the spreading behavior of the scheduler. This tracepoint helps understanding and debugging the conditions under which this happens. Signed-off-by:

Qais Yousef <qais.yousef@arm.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavankumar Kondeti <pkondeti@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Perret <quentin.perret@arm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de> Link: https://lkml.kernel.org/r/20190604111459.2862-6-qais.yousef@arm.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

include/trace/events/sched.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -621,6 +621,10 @@ DECLARE_TRACE(pelt_se_tp,
		TP_PROTO(struct sched_entity *se),
		TP_ARGS(se));

		DECLARE_TRACE(sched_overutilized_tp,
		TP_PROTO(struct root_domain *rd, bool overutilized),
		TP_ARGS(rd, overutilized));

		#endif /* _TRACE_SCHED_H */

		/* This part must be outside protection */

kernel/sched/fair.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -5181,8 +5181,10 @@ static inline bool cpu_overutilized(int cpu)

		static inline void update_overutilized_status(struct rq *rq)
		{
		if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu))
		if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) {
		WRITE_ONCE(rq->rd->overutilized, SG_OVERUTILIZED);
		trace_sched_overutilized_tp(rq->rd, SG_OVERUTILIZED);
		}
		}
		#else
		static inline void update_overutilized_status(struct rq *rq) { }
		@@ -8214,8 +8216,12 @@ next_group:

		/* Update over-utilization (tipping point, U >= 0) indicator */
		WRITE_ONCE(rd->overutilized, sg_status & SG_OVERUTILIZED);
		trace_sched_overutilized_tp(rd, sg_status & SG_OVERUTILIZED);
		} else if (sg_status & SG_OVERUTILIZED) {
		WRITE_ONCE(env->dst_rq->rd->overutilized, SG_OVERUTILIZED);
		struct root_domain *rd = env->dst_rq->rd;

		WRITE_ONCE(rd->overutilized, SG_OVERUTILIZED);
		trace_sched_overutilized_tp(rd, SG_OVERUTILIZED);
		}
		}

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