Commit-ID: f1d1be8aee6c461652aea8f58bedebaa73d7f4d3 Gitweb: https://git.kernel.org/tip/f1d1be8aee6c461652aea8f58bedebaa73d7f4d3 Author: Xunlei Pang <xlp...@linux.alibaba.com> AuthorDate: Wed, 20 Jun 2018 18:18:34 +0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 3 Jul 2018 09:17:29 +0200
sched/fair: Advance global expiration when period timer is restarted When period gets restarted after some idle time, start_cfs_bandwidth() doesn't update the expiration information, expire_cfs_rq_runtime() will see cfs_rq->runtime_expires smaller than rq clock and go to the clock drift logic, wasting needless CPU cycles on the scheduler hot path. Update the global expiration in start_cfs_bandwidth() to avoid frequent expire_cfs_rq_runtime() calls once a new period begins. Signed-off-by: Xunlei Pang <xlp...@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Ben Segall <bseg...@google.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/20180620101834.24455-2-xlp...@linux.alibaba.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/fair.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 791707c56886..840b92ee6f89 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5204,13 +5204,18 @@ static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) { + u64 overrun; + lockdep_assert_held(&cfs_b->lock); - if (!cfs_b->period_active) { - cfs_b->period_active = 1; - hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); - hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); - } + if (cfs_b->period_active) + return; + + cfs_b->period_active = 1; + overrun = hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); + cfs_b->runtime_expires += (overrun + 1) * ktime_to_ns(cfs_b->period); + cfs_b->expires_seq++; + hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); } static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
