Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755364AbbDGPnS (ORCPT ); Tue, 7 Apr 2015 11:43:18 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:57384 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755672AbbDGPnO (ORCPT ); Tue, 7 Apr 2015 11:43:14 -0400 Date: Tue, 7 Apr 2015 17:43:02 +0200 From: Peter Zijlstra To: Konstantin Khlebnikov Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Ben Segall , Roman Gushchin Subject: Re: [PATCH RFC] sched/fair: fix sudden expiration of cfq quota in put_prev_task() Message-ID: <20150407154302.GQ23123@twins.programming.kicks-ass.net> References: <20150403124138.1349.11633.stgit@buzz> <551E8CC5.30906@yandex-team.ru> <20150407125251.GM23123@twins.programming.kicks-ass.net> <20150407134758.GR24151@twins.programming.kicks-ass.net> <20150407151246.GS24151@twins.programming.kicks-ass.net> <5523F89F.1070502@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5523F89F.1070502@yandex-team.ru> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1687 Lines: 58 On Tue, Apr 07, 2015 at 06:32:47PM +0300, Konstantin Khlebnikov wrote: > On 07.04.2015 18:12, Peter Zijlstra wrote: > >On Tue, Apr 07, 2015 at 03:47:58PM +0200, Peter Zijlstra wrote: > >>Lemme think a bit more on that. > > > >So going by 734ff2a71f9e ("sched/rt: Fix picking RT and DL tasks from > >empty queue") something like this would be called for. > > > >--- > > kernel/sched/fair.c | 15 +++++++++++++++ > > 1 file changed, 15 insertions(+) > > > >diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > >index fdae26eb7218..1e47f816c976 100644 > >--- a/kernel/sched/fair.c > >+++ b/kernel/sched/fair.c > >@@ -5175,6 +5175,21 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev) > > return p; > > simple: > > cfs_rq = &rq->cfs; > > We don't need this if prev isn't from fair_sched_class: > first "goto simple" should go directly to "if (!cfs_rq->nr_running)". Just add that to the test here: > >+ if (cfs_bandwidth_used()) { > >+ /* > >+ * We may dequeue prev's cfs_rq in put_prev_task(). > >+ * So, we update time before cfs_rq->nr_running check. > >+ */ > >+ if (prev->on_rq) > >+ update_curr(cfs_rq); > >+ > >+ se = &prev->se; > >+ for_each_sched_entity(se) { > > Probably update_curr() should be inside loop too? Ah, yes, you're right. > >+ cfs_rq = cfs_rq_of(se); > >+ check_cfs_rq_runtime(cfs_rq); > >+ } > >+ } > > #endif > > > > if (!cfs_rq->nr_running) > > > > > -- > Konstantin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/