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sched/core: Add WARNING for multiple update_rq_clock() calls 

Now that we have no missing calls, add a warning to find multiple
calls.

By having only a single update_rq_clock() call per rq-lock section,
the section appears 'atomic' wrt time.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-10-03 16:53:49 +02:00 committed by Ingo Molnar
parent 3e777f9909
commit 26ae58d23b
2 changed files with 10 additions and 0 deletions
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3
kernel/sched/core.c
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@ -233,8 +233,11 @@ void update_rq_clock(struct rq *rq)
return;
#ifdef CONFIG_SCHED_DEBUG
if (sched_feat(WARN_DOUBLE_CLOCK))
SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
rq->clock_update_flags |= RQCF_UPDATED;
#endif
delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
if (delta < 0)
return;

7
kernel/sched/features.h
View File

@ -56,6 +56,13 @@ SCHED_FEAT(TTWU_QUEUE, true)
*/
SCHED_FEAT(SIS_AVG_CPU, false)
/*
* Issue a WARN when we do multiple update_rq_clock() calls
* in a single rq->lock section. Default disabled because the
* annotations are not complete.
*/
SCHED_FEAT(WARN_DOUBLE_CLOCK, false)
#ifdef HAVE_RT_PUSH_IPI
/*
* In order to avoid a thundering herd attack of CPUs that are