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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 716CCC4363A for ; Thu, 29 Oct 2020 17:59:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE7C520796 for ; Thu, 29 Oct 2020 17:59:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="2VqY6xxt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725849AbgJ2R7m (ORCPT ); Thu, 29 Oct 2020 13:59:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725775AbgJ2R7m (ORCPT ); Thu, 29 Oct 2020 13:59:42 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08407C0613CF for ; Thu, 29 Oct 2020 10:59:42 -0700 (PDT) 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=yYXY2ccmYEcpBjZVaiEIq5/m8qPCIZAO5UGU1CEFvAU=; b=2VqY6xxt+stJ3pGPjJ3+NuU0xP ERk+etg1R4P8v60qjKT9vh0EgGLSGIKW393MT01NZmdIlCmU7FjfUwizXFzkLfzmYiV3dJmBp4AgD YsXnStBMIItPTbUN5CGoqN070WASOisv1s5Awo8Mda9R+86beuSWpTeMZGtkwtsTxoNFqZSMn+FjH Clgxz482Hl+uImjeYE8LElBOteo3tWsIBeljvCvdbFHcscVkb3A596qttVqi4oSfMFNHchd/0BG0l m0Pc2cslfYXE2xFrvTIkAmG+vQlhmWcZywK7KNfoNqgH0Y612zWM8jxIngWtGkNU7R+bIVZMqBkFt omlKEeFg==; 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 1kYCCq-00052W-QB; Thu, 29 Oct 2020 17:59:25 +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 41DDC300455; Thu, 29 Oct 2020 18:59:23 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2E35A203C534D; Thu, 29 Oct 2020 18:59:23 +0100 (CET) Date: Thu, 29 Oct 2020 18:59:23 +0100 From: Peter Zijlstra To: Valentin Schneider Cc: tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de, qais.yousef@arm.com, swood@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vincent.donnefort@arm.com, tj@kernel.org, ouwen210@hotmail.com Subject: Re: [PATCH v4 17/19] sched: Add migrate_disable() tracepoints Message-ID: <20201029175923.GF2611@hirez.programming.kicks-ass.net> References: <20201023101158.088940906@infradead.org> <20201023102347.697960969@infradead.org> <20201029174302.GV2628@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 29, 2020 at 05:56:12PM +0000, Valentin Schneider wrote: > > On 29/10/20 17:43, Peter Zijlstra wrote: > > On Thu, Oct 29, 2020 at 04:27:26PM +0000, Valentin Schneider wrote: > >> Don't you want those directly after the ->migration_disabled write? > >> esp. for migrate_enable(), if that preempt_enable() leads to a context > >> switch then the disable->enable deltas won't reflect the kernel view. > >> > >> That delta may indeed include the time it took to run the stopper and > >> fix the task's affinity on migrate_enable(), but it could include all > >> sorts of other higher-priority tasks. > > > > I can put them in the preempt_disable() section I suppose, but these > > tracers should be looking at task_sched_runtime(), not walltime, and > > then the preemption doesn't matter. > > > > True. I was thinking of how to process it downstream, and the first thing > that came to mind was that rd->overutilized flag which we do monitor > fairly closely; however that is system-wide while migrate_disable() is > task-specific. > > > Also, a distinct lack of actual users atm.. :/ > > If you'd rather ditch this one altogether until someone asks for it, that > also works for me. Yeah, I can pull this patch until we get someone that actually needs it.