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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 ED4F0C2B9F8 for ; Tue, 25 May 2021 10:50:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C33516142B for ; Tue, 25 May 2021 10:50:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231286AbhEYKwE (ORCPT ); Tue, 25 May 2021 06:52:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230071AbhEYKwC (ORCPT ); Tue, 25 May 2021 06:52:02 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17A7EC061574 for ; Tue, 25 May 2021 03:50:31 -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=3yMiZmZluSw2WQWEbx30T7K0/rHONFze8eFE1k40vy4=; b=E5LM8zdkpvRG+vzhWbwzKvL2xr Q4YEZv51a8jsqziNUf0r4aqdeeuJVCmD6jjI9O6/wMkfjIcTTghCobk/xCjoe0nJRlvql8d486WZh 5RtjsloQyUlEnnJIKQuKMKmK37ICV7Q05Hhe2v8qZpt7WpiKzbGCGBljNzQGza/6qfmfGNx4Z6tOr MLpALDCrhGtbMkaievgExnkr9UaWKmG3LWHh7ovUkM26sVY7aB/FIRrMb3Z1yTJXXhfSc4KD2qAW2 4SRWugxaf5hRdam3LHTZrE5B4z4pR8Za0+kRdC2lsRoXN4n+sMyyJ2AagXPD3EPEB+4hGCIJH8apn flrf4mwg==; 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 (Red Hat Linux)) id 1llUch-003PQr-4v; Tue, 25 May 2021 10:49:31 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 34AAC3001E4; Tue, 25 May 2021 12:49:15 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1AA5720299B51; Tue, 25 May 2021 12:49:15 +0200 (CEST) Date: Tue, 25 May 2021 12:49:15 +0200 From: Peter Zijlstra To: changhuaixin Cc: Benjamin Segall , Dietmar Eggemann , dtcccc@linux.alibaba.com, Juri Lelli , khlebnikov@yandex-team.ru, open list , Mel Gorman , Ingo Molnar , Odin Ugedal , Odin Ugedal , pauld@redhead.com, Paul Turner , Steven Rostedt , Shanpei Chen , Tejun Heo , Vincent Guittot , xiyou.wangcong@gmail.com Subject: Re: [PATCH v5 1/3] sched/fair: Introduce the burstable CFS controller Message-ID: References: <20210520123419.8039-1-changhuaixin@linux.alibaba.com> <20210520123419.8039-2-changhuaixin@linux.alibaba.com> 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 Mon, May 24, 2021 at 08:42:03PM +0800, changhuaixin wrote: > >> --- a/kernel/sysctl.c > >> +++ b/kernel/sysctl.c > >> @@ -1816,6 +1816,15 @@ static struct ctl_table kern_table[] = { > >> .proc_handler = proc_dointvec_minmax, > >> .extra1 = SYSCTL_ONE, > >> }, > >> + { > >> + .procname = "sched_cfs_bw_burst_enabled", > >> + .data = &sysctl_sched_cfs_bw_burst_enabled, > >> + .maxlen = sizeof(unsigned int), > >> + .mode = 0644, > >> + .proc_handler = proc_dointvec_minmax, > >> + .extra1 = SYSCTL_ZERO, > >> + .extra2 = SYSCTL_ONE, > >> + }, > >> #endif > >> #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) > >> { > > > > What's the purpose of this new sysctl? By default it is disabled because > > burst==0, only if you set burst to some !0 value does this actually do > > anything. > > Originally, this is designed to turn burst feature off when the system becomes unstable. > Guess we can remove this as you have questioned it. Is stability a concern? This is CFS after all, if we overload, we simply share time as per usual. If there is a real use-case for a global knob to limit/disable this I don't object too much, but then please explicitly mention it.