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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, 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 F11F6C07E95 for ; Wed, 7 Jul 2021 11:18:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C110561C91 for ; Wed, 7 Jul 2021 11:18:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231359AbhGGLVX (ORCPT ); Wed, 7 Jul 2021 07:21:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231220AbhGGLVW (ORCPT ); Wed, 7 Jul 2021 07:21:22 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E17FC061574 for ; Wed, 7 Jul 2021 04:18:42 -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=o60E3y7ol8TaCCvWC0GHg5ui9lDE74SSRdsrHPhk1w0=; b=A7rEFuWmYtsEJwCpxd/swPsekG V+/DDDDEfi+KfK7AjXsq+jQNnTkI4hUob08H+nYYfJSfewjSqPVoCA0coUdHByEzUrLTG6OG6zt3Y mEwNJlvH+2XIgoNMQJjxpdeEB8Cp4JdrCmRklK8sG+RyBrm7qEL3XUttQLh1/6xSJ7kDQHO51h2r2 /+ZAdGa99Rwqra9/kiWWVR15+TdZxvrKI3WsLvLff53nFhqsIeZNQIUzBFwKQI/z6HHbc54l4oNU8 /CSIROINqWwvnmVTFfcKO3IxycpwwQYzwxwQ2aTA2Wzi7OOTpfqFjYAQy7lqgrk0E6qjg/h+27m1K NU3Urq0A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1m15Yq-00CLBY-7Y; Wed, 07 Jul 2021 11:17:52 +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 (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 607C5300233; Wed, 7 Jul 2021 13:17:46 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5009A2018A6F5; Wed, 7 Jul 2021 13:17:46 +0200 (CEST) Date: Wed, 7 Jul 2021 13:17:46 +0200 From: Peter Zijlstra To: Ani Sinha Cc: linux-kernel@vger.kernel.org, anirban.sinha@nokia.com, tglx@linutronix.de, Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira Subject: Re: [PATCH v2] sched/clock: print a log when the sched clock is marked unstable Message-ID: References: <20210707105659.194171-1-ani@anisinha.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210707105659.194171-1-ani@anisinha.ca> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 07, 2021 at 04:26:59PM +0530, Ani Sinha wrote: > When the sched clock transitions from stable to unstable and > vice versa, a kernel log is printed. When the sched clock > is marked explicitly as unstable, make __clear_sched_clock_stable() > emit a warning log. It is useful for example in understanding > why a certain feature like NOHZ that depends on availability of a > stable sched clock, is not available. > > Signed-off-by: Ani Sinha > --- > kernel/sched/clock.c | 1 + > 1 file changed, 1 insertion(+) > > Changelog: > V1: original patch > v2: print pr_warn from __clear_sched_clock_stable instead. Commit log > updated with proper prefix and wording. > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index c2b2859ddd82..99484fec0335 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -183,6 +183,7 @@ static void __clear_sched_clock_stable(void) > return; > > tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE); > + pr_warn("sched_clock: Marking unstable.\n"); > schedule_work(&sched_clock_work); > } I'm confused... that work has a ton of printk()s in, what is this pr_warn() adding?