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 3C57DC388F9 for ; Wed, 21 Oct 2020 12:20:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE3412224B for ; Wed, 21 Oct 2020 12:20:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YJBEdH4R" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2411680AbgJUMUT (ORCPT ); Wed, 21 Oct 2020 08:20:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2411613AbgJUMUT (ORCPT ); Wed, 21 Oct 2020 08:20:19 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B947EC0613CE; Wed, 21 Oct 2020 05:20:18 -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=hsnXQecX6kCtiiedXylMT/pwt2lPiF3DvQvxAo7NxUc=; b=YJBEdH4RgUxynHiucqfi042ohU j1kbmQoa2VWVFpmFYjz0BUM+jddWyWvrqLI+6RcuQUaMPpKpQ3iRfmPdFpEoKat2POKpv7FrE88tL fXEDv1lqBOn3goaqX3G7ACKU3Ix3u3nUbCvvpgWQXPghmbocxPRvJKbd9Ow38sFQpfSZ64kzHUPyf kyvY3mf7gcjeyXPb/gOkYd5TW+gwUKE+flKHJAof2T4JlnsWdGVPcMGuloJOdtiHGD/jdu8WfyU1C LGX/1p6V9ryaNgHkeQkNmMptTwEexVFar17/E72fbIgqrlz+9t67D1/Vh3uUSwn72cydob7cl50UU vdS3Ybqw==; 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 1kVD5u-0002d0-TD; Wed, 21 Oct 2020 12:19:55 +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 A7BC1304BAE; Wed, 21 Oct 2020 14:19:50 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 718E2203CC49D; Wed, 21 Oct 2020 14:19:50 +0200 (CEST) Date: Wed, 21 Oct 2020 14:19:50 +0200 From: Peter Zijlstra To: Julia Lawall Cc: Mel Gorman , Ingo Molnar , kernel-janitors@vger.kernel.org, Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, Valentin Schneider , Gilles Muller , "Rafael J. Wysocki" , viresh.kumar@linaro.org, srinivas.pandruvada@linux.intel.com Subject: Re: [PATCH] sched/fair: check for idle core Message-ID: <20201021121950.GF2628@hirez.programming.kicks-ass.net> References: <1603211879-1064-1-git-send-email-Julia.Lawall@inria.fr> <20201021112038.GC32041@suse.de> 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 Wed, Oct 21, 2020 at 01:56:55PM +0200, Julia Lawall wrote: > Prior to 5.8, my machine was using intel_pstate and had few background > tasks. Thus the problem wasn't visible in practice. Starting with 5.8 > the kernel decided that intel_cpufreq would be more appropriate, which > introduced kworkers every 0.004 seconds on all cores. That still doesn't make any sense. Are you running the legacy on-demand thing or something? Rafael, Srinivas, Viresh, how come it defaults to that? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Date: Wed, 21 Oct 2020 12:19:50 +0000 Subject: Re: [PATCH] sched/fair: check for idle core Message-Id: <20201021121950.GF2628@hirez.programming.kicks-ass.net> List-Id: References: <1603211879-1064-1-git-send-email-Julia.Lawall@inria.fr> <20201021112038.GC32041@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Julia Lawall Cc: Mel Gorman , Ingo Molnar , kernel-janitors@vger.kernel.org, Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, Valentin Schneider , Gilles Muller , "Rafael J. Wysocki" , viresh.kumar@linaro.org, srinivas.pandruvada@linux.intel.com On Wed, Oct 21, 2020 at 01:56:55PM +0200, Julia Lawall wrote: > Prior to 5.8, my machine was using intel_pstate and had few background > tasks. Thus the problem wasn't visible in practice. Starting with 5.8 > the kernel decided that intel_cpufreq would be more appropriate, which > introduced kworkers every 0.004 seconds on all cores. That still doesn't make any sense. Are you running the legacy on-demand thing or something? Rafael, Srinivas, Viresh, how come it defaults to that?