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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 108CBC43141 for ; Fri, 15 Nov 2019 13:46:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE41120715 for ; Fri, 15 Nov 2019 13:46:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PUqTHT4C" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727566AbfKONqe (ORCPT ); Fri, 15 Nov 2019 08:46:34 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:57842 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727249AbfKONqe (ORCPT ); Fri, 15 Nov 2019 08:46:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=wC+9uuEJp26Sj5A4rHzaYFSX5ziFMg0AaRJ7JE8csaM=; b=PUqTHT4C8uDgsWsoQ004rD5AI 6TrCbBj9b8PF9AYXQy5mO4S+YtrhDUba9Q02j5wUf32DvVWcI+oOZBDnOGcDBSZmU+aVoO3kyB0t1 mrlk1xGNKhEgZsjVyqhVDgLn5eJEkt2akcwzTA4nW1jW6Ncc2Yf9smYfo12ophM02Dhl8b/EDp5uK lHjuVluUavnUbUCdTwxUczBj9OSRnwTQUnbEiLOyrXf4LlZZvGLMktU5HxkMs1nEdR+a/CNa+GEr7 pX6C0CfDYX1hFxFDkdq9HENLAQg6Gd1oBovaTKJmptausmB/UwW8WA54eZtKHEwMXOXh2uDQeXpPw 7QQAtGkow==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iVbvK-0002Oo-9N; Fri, 15 Nov 2019 13:46:06 +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 325083006FB; Fri, 15 Nov 2019 14:44:55 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 523F72B12DAAC; Fri, 15 Nov 2019 14:46:03 +0100 (CET) Date: Fri, 15 Nov 2019 14:46:03 +0100 From: Peter Zijlstra To: Vincent Guittot Cc: linux-kernel , Ingo Molnar , Dietmar Eggemann , Juri Lelli , Steven Rostedt , Mel Gorman , Doug Smythies , "open list:THERMAL" , Linus Torvalds , Thomas Gleixner , Sargun Dhillon , Tejun Heo , Xie XiuQi , xiezhipeng1@huawei.com, Srinivas Pandruvada Subject: Re: [PATCH v4] sched/freq: move call to cpufreq_update_util Message-ID: <20191115134603.GK4131@hirez.programming.kicks-ass.net> References: <1573751251-3505-1-git-send-email-vincent.guittot@linaro.org> <20191115095447.GU4114@hirez.programming.kicks-ass.net> <20191115103735.GE4131@hirez.programming.kicks-ass.net> <20191115105110.GG4131@hirez.programming.kicks-ass.net> <20191115130144.GA4097@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 15, 2019 at 02:30:58PM +0100, Vincent Guittot wrote: > On Fri, 15 Nov 2019 at 14:02, Peter Zijlstra wrote: > > > > On Fri, Nov 15, 2019 at 12:03:31PM +0100, Vincent Guittot wrote: > > > > > This patch does 2 things: > > > - fix the spurious call to cpufreq just before attaching a task > > > > Right, so that one doesn't concern me too much. > > > > > - make sure cpufreq is still called when cfs is 0 but not irq/rt or dl > > > > But per the rq->has_blocked_load logic we would mostly stop sending > > events once we reach all 0s. > > > > Now, most of those updates will be through _nohz_idle_balance() -> > > update_nohz_stats(), which are remote, which means intel_pstate is > > ignoring them anyway. > > > > Now the _nohz_idle_balance() -> update_blocked_averages() thing runs > > local, and that will update the one random idle CPU we picked to run > > nohz balance, but all others will be left where they were. > > > > So why does intel_pstate care... Esp. on SKL+ with per-core P state this > > is of dubious value. > > Doug mentioned some periodic timers that were running on the CPUs > > > > > Also, and maybe I should go read back, why do we care what the P state > > is when we're mostly in C states anyway? These are all idle CPUs, > > otherwise we wouldkn't be running update_blocked_averages() on them > > anyway. > > AFAIU, there is not 100% idle but they have periodic timers that will > fire and run at higher P state If it is pure timers, I don't see how those CPUs end up calling cpufreq_update_util(). Per the above argument, only the CPU that ran nohz balance gets an update call, all the other CPUs that remain idle (or only serve IRQs) never get the call.