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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 58853C0650F for ; Thu, 8 Aug 2019 09:27:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 355292186A for ; Thu, 8 Aug 2019 09:27:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732247AbfHHJ1u (ORCPT ); Thu, 8 Aug 2019 05:27:50 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:38985 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730678AbfHHJ1t (ORCPT ); Thu, 8 Aug 2019 05:27:49 -0400 Received: by mail-wm1-f67.google.com with SMTP id u25so1677383wmc.4 for ; Thu, 08 Aug 2019 02:27:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=t+wAOarceN6JsDV9dX8Bi8ro/VvYkzelKra0BqUp7fk=; b=k79BVL0RLZuNPDDfl1d/Hmjwe1STALtAk0BZfEZnF5hamR8MFLRg1uqcevpxgqP+Xh f9gCRAhHUPUErwfKa+m3OVnSh2+e7ncX1H6z3sImuJvROgAk0tt6/UM5ki10CtNFjx/u 5HInzyOuZb/Sa1nAwIBCCDn/9TQrURRfPHmoTjbeBYZcOv82QU7uXHVEyC3sGLwMaKsA QRzel/dF8mKKDOgiAIoHgfR81pYtOtyXjnJbVYXrXNKvNJ1ZEqLXjIu8ur9ocDRw75be wJyqFQV7Yhnkdt1VOZWRVdBRcV3eJAEzcj8hLkLP+MEUq0hbL5Seg60ypiMLA6+SNdrS Q5mg== X-Gm-Message-State: APjAAAWAc5Fz4Oc3NntYdTQ13sGLzgx1isceLSLuBpQmemh13jL4IT4+ OV1FoMob9sN9xRA987/2SbLvN99W1l0= X-Google-Smtp-Source: APXvYqwQdsbKOEE/PwWPci5LuNpGGpEsb0wwQP/KJOMVuD3lmgo5CC655/acl5e9fAwDuJ0Hx+fUDA== X-Received: by 2002:a7b:c1c1:: with SMTP id a1mr3395947wmj.31.1565256467228; Thu, 08 Aug 2019 02:27:47 -0700 (PDT) Received: from localhost.localdomain ([151.29.237.107]) by smtp.gmail.com with ESMTPSA id k9sm29251813wrd.46.2019.08.08.02.27.45 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 08 Aug 2019 02:27:46 -0700 (PDT) Date: Thu, 8 Aug 2019 11:27:44 +0200 From: Juri Lelli To: Dietmar Eggemann Cc: Peter Zijlstra , mingo@kernel.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, bristot@redhat.com, balsini@android.com, dvyukov@google.com, tglx@linutronix.de, vpillai@digitalocean.com, rostedt@goodmis.org Subject: Re: [RFC][PATCH 12/13] sched/deadline: Introduce deadline servers Message-ID: <20190808092744.GI29310@localhost.localdomain> References: <20190726145409.947503076@infradead.org> <20190726161358.056107990@infradead.org> <34710762-f813-3913-0e55-fde7c91c6c2d@arm.com> <20190808075635.GB17205@worktop.programming.kicks-ass.net> <20cc05d3-0d0f-a558-2bbe-3b72527dd9bc@arm.com> <20190808084652.GG29310@localhost.localdomain> <99a8339d-8e06-bff8-284b-1829d0683a7a@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <99a8339d-8e06-bff8-284b-1829d0683a7a@arm.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/08/19 10:57, Dietmar Eggemann wrote: > On 8/8/19 10:46 AM, Juri Lelli wrote: > > On 08/08/19 10:11, Dietmar Eggemann wrote: > >> On 8/8/19 9:56 AM, Peter Zijlstra wrote: > >>> On Wed, Aug 07, 2019 at 06:31:59PM +0200, Dietmar Eggemann wrote: > >>>> On 7/26/19 4:54 PM, Peter Zijlstra wrote: > >>>>> > >>>>> > >>>>> Signed-off-by: Peter Zijlstra (Intel) > >>>> > >>>> [...] > >>>> > >>>>> @@ -889,6 +891,8 @@ static void update_curr(struct cfs_rq *c > >>>>> trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); > >>>>> cgroup_account_cputime(curtask, delta_exec); > >>>>> account_group_exec_runtime(curtask, delta_exec); > >>>>> + if (curtask->server) > >>>>> + dl_server_update(curtask->server, delta_exec); > >>>>> } > >>>> > >>>> I get a lockdep_assert_held(&rq->lock) related warning in start_dl_timer() > >>>> when running the full stack. > >>> > >>> That would seem to imply a stale curtask->server value; the hunk below: > >>> > >>> --- a/kernel/sched/core.c > >>> +++ b/kernel/sched/core.c > >>> @@ -3756,8 +3756,11 @@ pick_next_task(struct rq *rq, struct tas > >>> > >>> for_each_class(class) { > >>> p = class->pick_next_task(rq, NULL, NULL); > >>> - if (p) > >>> + if (p) { > >>> + if (p->sched_class == class && p->server) > >>> + p->server = NULL; > >>> return p; > >>> + } > >>> } > >>> > >>> > >>> Was supposed to clear p->server, but clearly something is going 'funny'. > >> > >> What about the fast path in pick_next_task()? > >> > >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > >> index bffe849b5a42..f1ea6ae16052 100644 > >> --- a/kernel/sched/core.c > >> +++ b/kernel/sched/core.c > >> @@ -3742,6 +3742,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) > >> if (unlikely(!p)) > >> p = idle_sched_class.pick_next_task(rq, prev, rf); > >> > >> + if (p->sched_class == &fair_sched_class && p->server) > >> + p->server = NULL; > >> + > > > > Hummm, but then who sets it back to the correct server. AFAIU > > update_curr() needs a ->server to do the correct DL accounting? > > Ah, OK, this would kill the whole functionality ;-) > I'm thinking we could use &rq->fair_server. It seems to pass the point we are discussing about, but then virt box becomes unresponsive (busy loops).