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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2100C54EAA for ; Mon, 30 Jan 2023 11:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235321AbjA3L5V (ORCPT ); Mon, 30 Jan 2023 06:57:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236250AbjA3L5Q (ORCPT ); Mon, 30 Jan 2023 06:57:16 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C332B17CF2 for ; Mon, 30 Jan 2023 03:57:03 -0800 (PST) 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=YEuLpyr1TFwAE2iDDlIo8sI/GlGMh4pgtBpr41lcQrg=; b=Jb51256Y486dJcgCTDFrwFQRzH f9dlUl3IKLS41mqn/iUPJaEplCGf8R0jaPVsZTSHL+cnWrA3figPzJhOk2mmyk09jOMjPFCvZzVvX FeERVfG7DR8wShu0vQ3Apske+ZXdt/6yBLAV/fQ/FC0Y4ytrv/FeT4O4CYodzOK/Z3fgSSELDDgAz +18vqtvJdQek5WA94sUpslK0EJNyO9OpE3XzlAy3DGBIkkT/lBVNtIuxVZ+q86Gj1wowlYuxb8/L9 E0JC4eZXqEKLFvpJ71VSpqXrsdvK0uEoMLatx7tIBjTzFUEfDiWVkYX0RnJ5RUgLgOAxEwYxGJ/0s b5QuAMvw==; 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 1pMSmA-00AKMV-Om; Mon, 30 Jan 2023 11:56:43 +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 A1D49300033; Mon, 30 Jan 2023 12:56:40 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 72C99238936D8; Mon, 30 Jan 2023 12:56:40 +0100 (CET) Date: Mon, 30 Jan 2023 12:56:40 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Will Deacon , Phil Auld , Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] sched: Store restrict_cpus_allowed_ptr() call state Message-ID: References: <20230127015527.466367-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230127015527.466367-1-longman@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 26, 2023 at 08:55:27PM -0500, Waiman Long wrote: > The user_cpus_ptr field was originally added by commit b90ca8badbd1 > ("sched: Introduce task_struct::user_cpus_ptr to track requested > affinity"). It was used only by arm64 arch due to possible asymmetric > CPU setup. > > Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested > cpumask"), task_struct::user_cpus_ptr is repurposed to store user > requested cpu affinity specified in the sched_setaffinity(). > > This results in a slight performance regression on an arm64 > system when booted with "allow_mismatched_32bit_el0" Dude, how can you still call this a slight performance regression after Will told you time and time again that's not the problem. It clearly is a behavioural problem.