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sched/debug: Add sched_overutilized tracepoint 

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>
This commit is contained in:
Qais Yousef 2019-06-04 12:14:58 +01:00 committed by Ingo Molnar
parent 8de6242cca
commit f9f240f96e
2 changed files with 12 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/trace/events/sched.h
View File

@ -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 */

10
kernel/sched/fair.c
View File

@ -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 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
/* 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);
}
}