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[2620:137:e000::1:20]) by mx.google.com with ESMTP id y63-20020a633242000000b005348977b5c5si18523500pgy.97.2023.07.03.05.16.47; Mon, 03 Jul 2023 05:17:00 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=Q0s11Ktj; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230094AbjGCMK1 (ORCPT + 99 others); Mon, 3 Jul 2023 08:10:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229873AbjGCMK0 (ORCPT ); Mon, 3 Jul 2023 08:10:26 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2ABAB109 for ; Mon, 3 Jul 2023 05:10:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=qGROpifsOdCT4Xwo5fTFRwrXOPLpnTQ2X2kSGJz1AGs=; b=Q0s11KtjRRE+XjqpowFprZ7h3z tT5HO09peI5vpMHiivblNnAxAVB2X7HOyFKL9MP91BInqwL4IPzWpNB+idLvVLdDy914nj6p1SIzT sitFrVZu5CnMlvsBuGiazlqbqXSGKCGlG8VSJ4sxDqxWQr7OefNt4MIqFvL6Bw8NXohS6Z37xHPmz Mud1HPm+6enB4Yj1G0ZaRmzPF/r4aNkMJyF+LKVn6cV6Z5zA8+3AuT87SCXW4EdhCPgS9XocdP194 AMnI047OiyUOwggEVYd5Sg+sOZy213Z4QbNYAs7HNeLYsFRsOJOY8zhfbI55ccHqw/LuIO/Lm2kMj zAxySWZQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qGINg-008DYd-9u; Mon, 03 Jul 2023 12:10:13 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3482C30005E; Mon, 3 Jul 2023 14:10:10 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1471D202A2A17; Mon, 3 Jul 2023 14:10:10 +0200 (CEST) Date: Mon, 3 Jul 2023 14:10:09 +0200 From: Peter Zijlstra To: Phil Auld Cc: linux-kernel@vger.kernel.org, Juri Lelli , Ingo Molnar , Daniel Bristot de Oliveira , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Ben Segall , Steven Rostedt , Mel Gorman , Frederic Weisbecker Subject: Re: [PATCH v4] Sched/fair: Block nohz tick_stop when cfs bandwidth in use Message-ID: <20230703121009.GH4253@hirez.programming.kicks-ass.net> References: <20230630135714.1018434-1-pauld@redhat.com> <20230630150641.GH2533791@hirez.programming.kicks-ass.net> <20230630152824.GC43299@lorien.usersys.redhat.com> <20230630160534.GA2534344@hirez.programming.kicks-ass.net> <20230630162910.GD43299@lorien.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230630162910.GD43299@lorien.usersys.redhat.com> X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 30, 2023 at 12:29:10PM -0400, Phil Auld wrote: > I think you are agreeing that I need the pick next code but need to remove > the hierarchy walks, right? Yeah, the dequeue case makes we have to care about pick, not sure we then also need to care about sched_update_tick_dependency() though. There is indeed a window where these two will 'race', but afaict it is benign.