From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752615AbeENLIJ (ORCPT ); Mon, 14 May 2018 07:08:09 -0400 Received: from forwardcorp1j.cmail.yandex.net ([5.255.227.105]:39411 "EHLO forwardcorp1j.cmail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028AbeENLIG (ORCPT ); Mon, 14 May 2018 07:08:06 -0400 Authentication-Results: smtpcorp1o.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Subject: [PATCH] sched: refill quota for current period when refilling timer activates From: Konstantin Khlebnikov To: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org Cc: Ben Segall Date: Mon, 14 May 2018 13:58:23 +0300 Message-ID: <152629550328.178124.4904326637886063654.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Period timer deactivates if task group has no activity during past period, i.e. if were no throttle and runtime from global pool weren't consumed. When timer activates back global pool contains unpredictable amount of expired runtime allocated long ago. In some cases this works fine and task could use it until next refill. But series short execution slices could drain all that leftovers because each switch expires local poll. In this case task group will be throttled until quota refill. This patch refills quota right at the moment of timer's activation. Signed-off-by: Konstantin Khlebnikov --- kernel/sched/fair.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 79f574dba096..b8d73ed17ff6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5165,6 +5165,8 @@ void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) if (!cfs_b->period_active) { cfs_b->period_active = 1; + /* refill quota for current period after inactivity */ + __refill_cfs_bandwidth_runtime(cfs_b); hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); }