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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EE558C56201 for ; Tue, 24 Nov 2020 12:05:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C9CB20857 for ; Tue, 24 Nov 2020 12:05:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="w7oCaXHR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387437AbgKXMFm (ORCPT ); Tue, 24 Nov 2020 07:05:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387427AbgKXMFl (ORCPT ); Tue, 24 Nov 2020 07:05:41 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60B84C0613D6 for ; Tue, 24 Nov 2020 04:05:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=ZPMTeBL5uTPVvPaAezchwqaTM/QZ2Ryp2lohK82OuMI=; b=w7oCaXHR+Ufy/R8pc+rYvAhXbc +HsTYgezirfDh+0OT9Rs/uAP1YFHMudci1ntBR/7b+gmgqhSg6h4VUuYFXXos3lQiz1FiucSvUVKk VQE+HcoQkFX7/Srf8Ei+UNqOUD0KXU02GPP2khoPbfUSEukZTir5/7i3r2bGO56+4S9sgeljW3xM3 ll/ls4gVCV4KHJ2Kw7DXYrZ1muDqz5k7xg+aGb1EnjN3MRhaYnlyL+B5252FkcuGYwkBrth+Qu5vQ 0o02NWbOZpJQRy8DYmi5JiXqhdmYY2qw+6A6UddDVSiM6dx1A26fDqgTUrscGeJNgc7gzulK90k4l OCSvFnEQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1khX3r-0006xj-EO; Tue, 24 Nov 2020 12:04:43 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 98AE83062EA; Tue, 24 Nov 2020 13:04:38 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7CF40200DB085; Tue, 24 Nov 2020 13:04:38 +0100 (CET) Date: Tue, 24 Nov 2020 13:04:38 +0100 From: Peter Zijlstra To: "Joel Fernandes (Google)" Cc: Nishanth Aravamudan , Julien Desfossez , Tim Chen , Vineeth Pillai , Aaron Lu , Aubrey Li , tglx@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , vineeth@bitbyteword.org, Chen Yu , Christian Brauner , Agata Gruza , Antonio Gomez Iglesias , graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com, pjt@google.com, rostedt@goodmis.org, derkling@google.com, benbjiang@tencent.com, Alexandre Chartre , James.Bottomley@hansenpartnership.com, OWeisse@umich.edu, Dhaval Giani , Junaid Shahid , jsbarnes@google.com, chris.hyser@oracle.com, Ben Segall , Josh Don , Hao Luo , Tom Lendacky , Aubrey Li , "Paul E. McKenney" , Tim Chen Subject: Re: [PATCH -tip 12/32] sched: Simplify the core pick loop for optimized case Message-ID: <20201124120438.GY3021@hirez.programming.kicks-ass.net> References: <20201117232003.3580179-1-joel@joelfernandes.org> <20201117232003.3580179-13-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201117232003.3580179-13-joel@joelfernandes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 17, 2020 at 06:19:42PM -0500, Joel Fernandes (Google) wrote: > + /* > + * Optimize for common case where this CPU has no cookies > + * and there are no cookied tasks running on siblings. > + */ > + if (!need_sync) { > + for_each_class(class) { > + next = class->pick_task(rq); > + if (next) > + break; > + } > + > + if (!next->core_cookie) { > + rq->core_pick = NULL; > + goto done; > + } > need_sync = true; > } This isn't what I send you here: https://lkml.kernel.org/r/20201026093131.GF2628@hirez.programming.kicks-ass.net Specifically, you've lost the whole cfs-cgroup optimization. What was wrong/not working with the below? --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5225,8 +5227,6 @@ pick_next_task(struct rq *rq, struct tas return next; } - put_prev_task_balance(rq, prev, rf); - smt_mask = cpu_smt_mask(cpu); need_sync = !!rq->core->core_cookie; @@ -5255,17 +5255,14 @@ pick_next_task(struct rq *rq, struct tas * and there are no cookied tasks running on siblings. */ if (!need_sync) { - for_each_class(class) { - next = class->pick_task(rq); - if (next) - break; - } - + next = __pick_next_task(rq, prev, rf); if (!next->core_cookie) { rq->core_pick = NULL; - goto done; + return next; } - need_sync = true; + put_prev_task(next); + } else { + put_prev_task_balance(rq, prev, rf); } for_each_cpu(i, smt_mask) {