From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7F13C43218 for ; Tue, 11 Jun 2019 13:50:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A95720896 for ; Tue, 11 Jun 2019 13:50:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="wR1Xo3Sp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391300AbfFKNuV (ORCPT ); Tue, 11 Jun 2019 09:50:21 -0400 Received: from merlin.infradead.org ([205.233.59.134]:54872 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387866AbfFKNuV (ORCPT ); Tue, 11 Jun 2019 09:50:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=weJ+BdbI8Q90N8a+OOAeypEBoVRkubIK5bltMKMV/f0=; b=wR1Xo3SpqWqwzufYCGoJxXd+P IX0sP1A8tp4aRwAT5IqhpOi2dNXgSvBe1FCTDtZHZY9Zj+lLAbAtc3MZk8qSXSqQYeDT+RXVpJmhF h5xgpBXkw/beP8Om3U//CtYWl7NYimwKd028qGjhTEgtQgv+IKsWNJTsuRCDYulmAzNAhZUS+t6eH 4Qf/wVhya/c4D41yJOEcSy9sgEjyVd4DUuWN/5lkpGKkDv6vgIbgCdZ9reyfJmVT9U0gNolWDDfhz WXJS892PRO+ujgCUf23gn5Qoo49FxwfC61Nn7f/EqX13LdgQsN5HxlDRGvrz+orUb56dlRCWBNQTM YvS9hU1Bw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hahAC-0004pJ-Kz; Tue, 11 Jun 2019 13:50:12 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3842520236A40; Tue, 11 Jun 2019 15:50:11 +0200 (CEST) Date: Tue, 11 Jun 2019 15:50:11 +0200 From: Peter Zijlstra To: Phil Auld Cc: bsegall@google.com, linux-kernel@vger.kernel.org, Xunlei Pang , Ingo Molnar Subject: Re: [PATCH v2] sched/fair: don't push cfs_bandwith slack timers forward Message-ID: <20190611135011.GX3436@hirez.programming.kicks-ass.net> References: <20190611130417.GA15412@pauld.bos.csb> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190611130417.GA15412@pauld.bos.csb> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > Reviewed-by: Xunlei Pang > > --- > > 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 Thanks! Should this patch have a Fixes: tag?