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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 BE66AC282C3 for ; Tue, 22 Jan 2019 17:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B05F21726 for ; Tue, 22 Jan 2019 17:13:29 +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="MSi3ddBE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729591AbfAVRN1 (ORCPT ); Tue, 22 Jan 2019 12:13:27 -0500 Received: from merlin.infradead.org ([205.233.59.134]:34346 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729316AbfAVRN1 (ORCPT ); Tue, 22 Jan 2019 12:13:27 -0500 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: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=5mX3uOPs0Ea+SwmTP+PBPfXEY8NCxY+CmKxc5I2qaOQ=; b=MSi3ddBEszx/AT5tjeydVGqNX tb5FTrpkTlVofYEyYaDyR8nxzQ849MjwLx3ujFBjgbgFuO/ld7LbJLFQmXAP+Vwg3XbUM06mIUVNL zwj+qNOmkXFl8WhR2N/Cgugkylhdt9rRkiBRskFn0fc3Jv9QV4o12Y/oTT0ypoHbSnkKlWFKU2DyW kOd0oiiN5pEzvwD1ZLMIR6W5efudpaKChjPn16V14lc3AHyfIWdwZpQqGng/xhTtqSItpW+1WibvY V7ukLeMloMwGBz3s7h1QTzDv0lpZb9oVG/zJ3uxjWAGC1kwR1Fah/ECkmVwIL+u6Ce4SMdLC0lYzR 9Swbt2apg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1glzbw-0005Al-LX; Tue, 22 Jan 2019 17:13:17 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 213042042CFC2; Tue, 22 Jan 2019 18:13:14 +0100 (CET) Date: Tue, 22 Jan 2019 18:13:14 +0100 From: Peter Zijlstra To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-api@vger.kernel.org, Ingo Molnar , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v6 08/16] sched/cpufreq: uclamp: Add utilization clamping for FAIR tasks Message-ID: <20190122171314.GS27931@hirez.programming.kicks-ass.net> References: <20190115101513.2822-1-patrick.bellasi@arm.com> <20190115101513.2822-9-patrick.bellasi@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190115101513.2822-9-patrick.bellasi@arm.com> 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 Tue, Jan 15, 2019 at 10:15:05AM +0000, Patrick Bellasi wrote: > @@ -342,11 +350,24 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, > return; > sg_cpu->iowait_boost_pending = true; > > + /* > + * Boost FAIR tasks only up to the CPU clamped utilization. > + * > + * Since DL tasks have a much more advanced bandwidth control, it's > + * safe to assume that IO boost does not apply to those tasks. I'm not buying that argument. IO-boost isn't related to b/w management. IO-boot is more about compensating for hidden dependencies, and those don't get less hidden for using a different scheduling class. Now, arguably DL should not be doing IO in the first place, but that's a whole different discussion. > + * Instead, since RT tasks are not utilization clamped, we don't want > + * to apply clamping on IO boost while there is blocked RT > + * utilization. > + */ > + max_boost = sg_cpu->iowait_boost_max; > + if (!cpu_util_rt(cpu_rq(sg_cpu->cpu))) > + max_boost = uclamp_util(cpu_rq(sg_cpu->cpu), max_boost); > + > /* Double the boost at each request */ > if (sg_cpu->iowait_boost) { > sg_cpu->iowait_boost <<= 1; > - if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max) > - sg_cpu->iowait_boost = sg_cpu->iowait_boost_max; > + if (sg_cpu->iowait_boost > max_boost) > + sg_cpu->iowait_boost = max_boost; > return; > } Hurmph... so I'm not sold on this bit.