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_2 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 9BF79C7618B for ; Fri, 26 Jul 2019 10:18:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73D5422ADA for ; Fri, 26 Jul 2019 10:18:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726215AbfGZKS1 (ORCPT ); Fri, 26 Jul 2019 06:18:27 -0400 Received: from mail.santannapisa.it ([193.205.80.98]:54369 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725815AbfGZKS0 (ORCPT ); Fri, 26 Jul 2019 06:18:26 -0400 Received: from [151.41.39.6] (account l.abeni@santannapisa.it HELO sweethome) by santannapisa.it (CommuniGate Pro SMTP 6.1.11) with ESMTPSA id 141117354; Fri, 26 Jul 2019 12:18:24 +0200 Date: Fri, 26 Jul 2019 12:18:19 +0200 From: luca abeni To: Dietmar Eggemann Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Daniel Bristot de Oliveira , Valentin Schneider , Qais Yousef , linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] sched/deadline: Use return value of SCHED_WARN_ON() in bw accounting Message-ID: <20190726121819.32be6fb1@sweethome> In-Reply-To: <20190726082756.5525-6-dietmar.eggemann@arm.com> References: <20190726082756.5525-1-dietmar.eggemann@arm.com> <20190726082756.5525-6-dietmar.eggemann@arm.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dietmar, On Fri, 26 Jul 2019 09:27:56 +0100 Dietmar Eggemann wrote: > To make the decision whether to set rq or running bw to 0 in underflow > case use the return value of SCHED_WARN_ON() rather than an extra if > condition. I think I tried this at some point, but if I remember well this solution does not work correctly when SCHED_DEBUG is not enabled. Luca > > Signed-off-by: Dietmar Eggemann > --- > kernel/sched/deadline.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index a9cb52ceb761..66c594b5507e 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -95,8 +95,7 @@ void __sub_running_bw(u64 dl_bw, struct dl_rq > *dl_rq) > lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); > dl_rq->running_bw -= dl_bw; > - SCHED_WARN_ON(dl_rq->running_bw > old); /* underflow */ > - if (dl_rq->running_bw > old) > + if (SCHED_WARN_ON(dl_rq->running_bw > old)) /* underflow */ > dl_rq->running_bw = 0; > /* kick cpufreq (see the comment in kernel/sched/sched.h). */ > cpufreq_update_util(rq_of_dl_rq(dl_rq), 0); > @@ -119,8 +118,7 @@ void __sub_rq_bw(u64 dl_bw, struct dl_rq *dl_rq) > > lockdep_assert_held(&(rq_of_dl_rq(dl_rq))->lock); > dl_rq->this_bw -= dl_bw; > - SCHED_WARN_ON(dl_rq->this_bw > old); /* underflow */ > - if (dl_rq->this_bw > old) > + if (SCHED_WARN_ON(dl_rq->this_bw > old)) /* underflow */ > dl_rq->this_bw = 0; > SCHED_WARN_ON(dl_rq->running_bw > dl_rq->this_bw); > }