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Groups > linux.kernel > #1642299

Re: [PATCH RESEND 1/1] sched/rt: minimize rq->lock contention in, do_sched_rt_period_timer()

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH RESEND 1/1] sched/rt: minimize rq->lock contention in, do_sched_rt_period_timer()
Date 2017-05-16 10:20 +0200
Message-ID <tHFS1-3bj-17@gated-at.bofh.it> (permalink)
References <tHtHc-3KQ-5@gated-at.bofh.it> <tHtHc-3KQ-19@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, May 15, 2017 at 02:14:13PM -0500, Dave Kleikamp wrote:
> With CONFIG_RT_GROUP_SCHED defined, do_sched_rt_period_timer() sequentially
> takes each cpu's rq->lock. On a large, busy system, the cumulative time it
> takes to acquire each lock can be excessive, even triggering a watchdog
> timeout.
> 
> If rt_rq_rt_time and rt_rq->rt_nr_running are both zero, this function does
> nothing while holding the lock, so don't bother taking it at all.

Indeed, thanks Dave!

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[PATCH RESEND 0/1] sched/rt: minimize rq->lock contention in,  do_sched_rt_period_timer() Dave Kleikamp <dave.kleikamp@oracle.com> - 2017-05-15 21:20 +0200
  [PATCH RESEND 1/1] sched/rt: minimize rq->lock contention in,  do_sched_rt_period_timer() Dave Kleikamp <dave.kleikamp@oracle.com> - 2017-05-15 21:20 +0200
    Re: [PATCH RESEND 1/1] sched/rt: minimize rq->lock contention in,  do_sched_rt_period_timer() Peter Zijlstra <peterz@infradead.org> - 2017-05-16 10:20 +0200
    [tip:sched/core] sched/rt: Minimize rq->lock contention in  do_sched_rt_period_timer() tip-bot for Dave Kleikamp <tipbot@zytor.com> - 2017-05-23 11:00 +0200

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