From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5511C15EFAD for ; Wed, 24 Apr 2024 15:21:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713972070; cv=none; b=NjrAvzAzi/doR2nkRWkJ02KiUxhL8IMCH0C0chHvkviFiRpqsmNc/Q726/KZk99TPPbrRjOuV8OkBYpkIu1sf/Vyyfl9sHsdAYbmr3fIw6eayoY2YXZHe1iqLoyOGTGxWVBOZmPnmfkBxUMnpp45TUzNWk1v/dzLIWeNHGl2Ls4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713972070; c=relaxed/simple; bh=q1exOMXTIOd9tdMTIymwsETDLgVuZhekuD/4BzdFroE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A5EFV/wMfdRx6Dq0Jrt5ur+JWDgfeCzmwQRJg8xe/QovbZxEhgHM6rr75/YQHb51yOaqe/kXTACHbN+8JqbVSkwXubtX4aZ9xov9j1tKpCh0YnCyKa7AQk6fVT8EKQbHD4/nmfBbDva5H437rbSa88IGbu/iH4Zu2en59+FbyA4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=mqMzFLk6; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mqMzFLk6" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=1BnmcBKajNjGf36OXNjueaNFKhQAlEqsZTRopkafH8Q=; b=mqMzFLk68bVQeWWZ2Z1gXeq8/U 0A52ko5Kh63k6l4n6DrP9lI2V8jY4fk4viTtgGnyDRI1q40OsiNsmFJfqsTypbJUKMEG8o/Pp4fBv o5y/7PqJvNoESukcq/mYtmVJ5eSoQuDVplsod69b5nBZ1pEDwVTts6AJH0kdOgFiq3b2RFmcZJMLk 2HQWjCJOL/rVgW0XqYkz04r9rbS2KJYFSHkOYA49B6GTnDwqibow5dYUJ+KtXwVaFX3wHZP+Y6Nvk lsQFtIKn649q2EITEWItFjCAODkXPpeEs+aGhheatzET3tibvn6C7Fz46G1OXjg7QBjHIxtGH5mf9 DTXCrfJA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1rzeQO-0000000EQr3-3BVc; Wed, 24 Apr 2024 15:20:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 60D3E30040C; Wed, 24 Apr 2024 17:20:44 +0200 (CEST) Date: Wed, 24 Apr 2024 17:20:44 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: K Prateek Nayak , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org, wuyun.abel@bytedance.com, tglx@linutronix.de, Chen Yu , Oliver Sang Subject: Re: [RFC][PATCH 08/10] sched/fair: Implement delayed dequeue Message-ID: <20240424152044.GS30852@noisy.programming.kicks-ass.net> References: <20240405102754.435410987@infradead.org> <20240405110010.631664251@infradead.org> <557be85d-e1c1-0835-eebd-f76e32456179@amd.com> <14330cf4-8d9e-1e55-7717-653b800e5cee@amd.com> <747627a1414f1f33d0c237f555494149d6937800.camel@gmx.de> <2b9f7617f2b2130bb6270504ec3858f15d463f1d.camel@gmx.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2b9f7617f2b2130bb6270504ec3858f15d463f1d.camel@gmx.de> On Thu, Apr 18, 2024 at 06:24:59PM +0200, Mike Galbraith wrote: > Greetings, > > I tossed a couple rocks at it today, and seem to have hit the little > bugger. The root cause seems to be doing the delay dequeue business on > exiting tasks. Hunk #1 of hacklet below seems to quell the explosions. > Neat, Thanks! I was just about ready to go look at this again. > > --- > kernel/sched/fair.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5374,6 +5374,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, st > update_curr(cfs_rq); > > if (sched_feat(DELAY_DEQUEUE) && sleep && > + !(entity_is_task(se) && (task_of(se)->flags & PF_EXITING)) && > !entity_eligible(cfs_rq, se)) { > if (cfs_rq->next == se) > cfs_rq->next = NULL; > @@ -5495,14 +5496,14 @@ pick_next_entity(struct rq *rq, struct c > } > > struct sched_entity *se = pick_eevdf(cfs_rq); > - if (se->sched_delayed) { > + while (se && se->sched_delayed) { > dequeue_entities(rq, se, DEQUEUE_SLEEP | DEQUEUE_DELAYED); > SCHED_WARN_ON(se->sched_delayed); > SCHED_WARN_ON(se->on_rq); > if (sched_feat(DELAY_ZERO) && se->vlag > 0) > se->vlag = 0; > > - return NULL; > + se = pick_eevdf(cfs_rq); > } > return se; > } >