Messages in this thread | | | Date | Tue, 11 Jun 2019 15:50:11 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] sched/fair: don't push cfs_bandwith slack timers forward |
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On Tue, Jun 11, 2019 at 09:04:17AM -0400, Phil Auld wrote: > On Thu, Jun 06, 2019 at 10:21:01AM -0700 bsegall@google.com wrote: > > When a cfs_rq sleeps and returns its quota, we delay for 5ms before > > waking any throttled cfs_rqs to coalesce with other cfs_rqs going to > > sleep, as this has to be done outside of the rq lock we hold. > > > > The current code waits for 5ms without any sleeps, instead of waiting > > for 5ms from the first sleep, which can delay the unthrottle more than > > we want. Switch this around so that we can't push this forward forever. > > > > This requires an extra flag rather than using hrtimer_active, since we > > need to start a new timer if the current one is in the process of > > finishing. > > > > Signed-off-by: Ben Segall <bsegall@google.com> > > Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com> > > --- > > kernel/sched/fair.c | 7 +++++++ > > kernel/sched/sched.h | 1 + > > 2 files changed, 8 insertions(+) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 8213ff6e365d..2ead252cfa32 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -4729,6 +4729,11 @@ static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) > > if (runtime_refresh_within(cfs_b, min_left)) > > return; > > > > + /* don't push forwards an existing deferred unthrottle */ > > + if (cfs_b->slack_started) > > + return; > > + cfs_b->slack_started = true; > > + > > hrtimer_start(&cfs_b->slack_timer, > > ns_to_ktime(cfs_bandwidth_slack_period), > > HRTIMER_MODE_REL); > > @@ -4782,6 +4787,7 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) > > > > /* confirm we're still not at a refresh boundary */ > > raw_spin_lock_irqsave(&cfs_b->lock, flags); > > + cfs_b->slack_started = false; > > if (cfs_b->distribute_running) { > > raw_spin_unlock_irqrestore(&cfs_b->lock, flags); > > return; > > @@ -4920,6 +4926,7 @@ void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) > > hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > > cfs_b->slack_timer.function = sched_cfs_slack_timer; > > cfs_b->distribute_running = 0; > > + cfs_b->slack_started = false; > > } > > > > static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > > index efa686eeff26..60219acda94b 100644 > > --- a/kernel/sched/sched.h > > +++ b/kernel/sched/sched.h > > @@ -356,6 +356,7 @@ struct cfs_bandwidth { > > u64 throttled_time; > > > > bool distribute_running; > > + bool slack_started; > > #endif > > }; > > > > -- > > 2.22.0.rc1.257.g3120a18244-goog > > > > I think this looks good. I like not delaying that further even if it > does not fix Dave's use case. > > It does make it glaring that I should have used false/true for setting > distribute_running though :) > > > Acked-by: Phil Auld <pauld@redhat.com>
Thanks!
Should this patch have a Fixes: tag?
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