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 372F7C388F9 for ; Wed, 21 Oct 2020 12:52:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE1C322248 for ; Wed, 21 Oct 2020 12:52:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Viwr+En7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442676AbgJUMw2 (ORCPT ); Wed, 21 Oct 2020 08:52:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2440686AbgJUMw2 (ORCPT ); Wed, 21 Oct 2020 08:52:28 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DB12C0613CE; Wed, 21 Oct 2020 05:52:28 -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=Uq5uoGCfFjFseaKYtetVeX6eT0EP/TsERuBq6LOZk28=; b=Viwr+En7j03ibYqEEkgIXLWjwm uoFtHwXEVjyaPwD5mUXxPpH/k55ZSM2o+5sGbVHB477cW8yBE2SigNf+qDScZPo9e5HT4fDjzbODM KQ84HwFNcF3jovtgNhIV/gYosM632W3GCdZGJVDpCEkItzhZ9dXCmMvOK6iU99AQwXB4aCbDsqi+n 0Qj88YRBZV+rjtuuWW2IeGyyLavF1iszNTKlyVwfQEBSf1Bs4c4y2yyUghgoFNKOiOWrxdtaL2FSv eeHD/W66+MnL/9vzKvoBJAw0at/KEAy/cQltrbMHyzIpZG1DA8mh16lATxDCSTJZyUV53r9BGPkWq lew1craw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVDb3-0007Bh-1V; Wed, 21 Oct 2020 12:52:05 +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 A5619302753; Wed, 21 Oct 2020 14:52:03 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 717C82BA9E6D3; Wed, 21 Oct 2020 14:52:03 +0200 (CEST) Date: Wed, 21 Oct 2020 14:52:03 +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: <20201021125203.GG2628@hirez.programming.kicks-ass.net> References: <1603211879-1064-1-git-send-email-Julia.Lawall@inria.fr> <20201021112038.GC32041@suse.de> <20201021121950.GF2628@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 Wed, Oct 21, 2020 at 02:42:20PM +0200, Julia Lawall wrote: > > > On Wed, 21 Oct 2020, Peter Zijlstra wrote: > > > 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? > > The relevant commits are 33aa46f252c7, and 39a188b88332 that fixes a small > bug. I have a Intel(R) Xeon(R) CPU E7-8870 v4 @ 2.10GHz that does not > have the HWP feature, even though the cores seemed to be able to change > their frequencies at the hardware level. That just makes intel_pstate not prefer active mode. With the clear intent that it should then go use schedutil, but somehow it looks like you landed on ondemand, which is absolutely atrocious. What's: $ for i in /sys/devices/system/cpu/cpu0/cpufreq/scaling_*; do echo -n $i ": "; cat $i; done say, for you? And if you do: $ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo schedutil > $i; done Are the kworkers gone?