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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 85DCEC433E0 for ; Mon, 22 Jun 2020 09:11:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 60358206D7 for ; Mon, 22 Jun 2020 09:11:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726530AbgFVJLl (ORCPT ); Mon, 22 Jun 2020 05:11:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:34164 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725983AbgFVJLk (ORCPT ); Mon, 22 Jun 2020 05:11:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3A3C013ABD; Mon, 22 Jun 2020 09:11:36 +0000 (UTC) Date: Mon, 22 Jun 2020 10:11:22 +0100 From: Mel Gorman To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, paulmck@kernel.org, frederic@kernel.org Subject: Re: [PATCH 1/6] sched: Fix ttwu_queue_cond() Message-ID: <20200622091122.GG3129@suse.de> References: <20200615125654.678940605@infradead.org> <20200615131143.130326165@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20200615131143.130326165@infradead.org> 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 Mon, Jun 15, 2020 at 02:56:55PM +0200, Peter Zijlstra wrote: > Where the condition: > > !cpus_share_cache(smp_processor_id(), cpu) > > already implies 'cpu != smp_processor_id()', because a CPU always > shares cache with itself, the secondary condition added in commit: > > 2ebb17717550 ("sched/core: Offload wakee task activation if it the wakee is descheduling") > > voids that implication, resulting in attempting to do local wake-ups > through the queue mechanism. > > Fixes: 2ebb17717550 ("sched/core: Offload wakee task activation if it the wakee is descheduling") > Reported-by: Paul E. McKenney > Signed-off-by: Peter Zijlstra (Intel) > Tested-by: Paul E. McKenney Yep, I mistakenly though this would be covered by the self-wakeup check early in try_to_wake_up() but it is not Acked-by: Mel Gorman -- Mel Gorman SUSE Labs