From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932387AbbJMDoP (ORCPT ); Mon, 12 Oct 2015 23:44:15 -0400 Received: from mga01.intel.com ([192.55.52.88]:48302 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932278AbbJMDoL (ORCPT ); Mon, 12 Oct 2015 23:44:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,676,1437462000"; d="scan'208";a="791171813" Date: Tue, 13 Oct 2015 03:55:17 +0800 From: Yuyang Du To: Mike Galbraith Cc: Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: 4.3 group scheduling regression Message-ID: <20151012195516.GM11102@intel.com> References: <20151010170142.GI3816@twins.programming.kicks-ass.net> <1444530318.3363.40.camel@gmail.com> <1444585321.4169.18.camel@gmail.com> <20151012072344.GM3604@twins.programming.kicks-ass.net> <1444635897.3425.19.camel@gmail.com> <20151012080407.GJ3816@twins.programming.kicks-ass.net> <20151012005351.GJ11102@intel.com> <20151012091206.GK3816@twins.programming.kicks-ass.net> <20151012021230.GK11102@intel.com> <1444645411.3534.5.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1444645411.3534.5.camel@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 12, 2015 at 12:23:31PM +0200, Mike Galbraith wrote: > On Mon, 2015-10-12 at 10:12 +0800, Yuyang Du wrote: > > > I am guessing it is in calc_tg_weight(), and naughty boys do make them more > > favored, what a reality... > > > > Mike, beg you test the following? > > Wow, that was quick. Dinky patch made it all better. > > ----------------------------------------------------------------------------------------------------------------- > Task | Runtime ms | Switches | Average delay ms | Maximum delay ms | Maximum delay at | > ----------------------------------------------------------------------------------------------------------------- > oink:(8) | 739056.970 ms | 27270 | avg: 2.043 ms | max: 29.105 ms | max at: 339.988310 s > mplayer:(25) | 36448.997 ms | 44670 | avg: 1.886 ms | max: 72.808 ms | max at: 302.153121 s > Xorg:988 | 13334.908 ms | 22210 | avg: 0.081 ms | max: 25.005 ms | max at: 269.068666 s > testo:(9) | 2558.540 ms | 13703 | avg: 0.124 ms | max: 6.412 ms | max at: 279.235272 s > konsole:1781 | 1084.316 ms | 1457 | avg: 0.006 ms | max: 1.039 ms | max at: 268.863379 s > kwin:1734 | 879.645 ms | 17855 | avg: 0.458 ms | max: 15.788 ms | max at: 268.854992 s > pulseaudio:1808 | 356.334 ms | 15023 | avg: 0.028 ms | max: 6.134 ms | max at: 324.479766 s > threaded-ml:3483 | 292.782 ms | 25769 | avg: 0.364 ms | max: 40.387 ms | max at: 294.550515 s > plasma-desktop:1745 | 265.055 ms | 1470 | avg: 0.102 ms | max: 21.886 ms | max at: 267.724902 s > perf:3439 | 61.677 ms | 2 | avg: 0.117 ms | max: 0.232 ms | max at: 367.043889 s Phew... I think maybe the real disease is the tg->load_avg is not updated in time. I.e., it is after migrate, the source cfs_rq does not decrease its contribution to the parent's tg->load_avg fast enough. -- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4df37a4..3dba883 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2686,12 +2686,13 @@ static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) { struct sched_avg *sa = &cfs_rq->avg; - int decayed; + int decayed, updated = 0; if (atomic_long_read(&cfs_rq->removed_load_avg)) { long r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); sa->load_avg = max_t(long, sa->load_avg - r, 0); sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0); + updated = 1; } if (atomic_long_read(&cfs_rq->removed_util_avg)) { @@ -2708,7 +2709,7 @@ static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) cfs_rq->load_last_update_time_copy = sa->last_update_time; #endif - return decayed; + return decayed | updated; } /* Update task and its cfs_rq load average */