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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFB19EC8742 for ; Thu, 7 Sep 2023 18:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344238AbjIGSmC (ORCPT ); Thu, 7 Sep 2023 14:42:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344267AbjIGSmA (ORCPT ); Thu, 7 Sep 2023 14:42:00 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5B11D1700; Thu, 7 Sep 2023 11:41:55 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 838661762; Thu, 7 Sep 2023 06:45:34 -0700 (PDT) Received: from [10.57.92.126] (unknown [10.57.92.126]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0C7E3F766; Thu, 7 Sep 2023 06:44:54 -0700 (PDT) Message-ID: <8657cc7c-169b-3479-5919-72bd39335b15@arm.com> Date: Thu, 7 Sep 2023 14:45:30 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Content-Language: en-US To: Peter Zijlstra Cc: Qais Yousef , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Ingo Molnar , Dietmar Eggemann , Vincent Guittot , Viresh Kumar , bristot@redhat.com, juri.lelli@redhat.com References: <20230827233203.1315953-1-qyousef@layalina.io> <20230906211850.zyvk6qtt6fvpxaf3@airbuntu> <6011d8bb-9a3b-1435-30b0-d75b39bf5efa@arm.com> <20230907115307.GD10955@noisy.programming.kicks-ass.net> <89067f71-9b83-e647-053e-07f7d55b6529@arm.com> <20230907132906.GG10955@noisy.programming.kicks-ass.net> <5616e50d-b827-4547-5b16-9131ace98419@arm.com> <20230907133840.GH10955@noisy.programming.kicks-ass.net> From: Lukasz Luba In-Reply-To: <20230907133840.GH10955@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 9/7/23 14:38, Peter Zijlstra wrote: > On Thu, Sep 07, 2023 at 02:33:49PM +0100, Lukasz Luba wrote: >> >> >> On 9/7/23 14:29, Peter Zijlstra wrote: >>> On Thu, Sep 07, 2023 at 02:06:15PM +0100, Lukasz Luba wrote: >>> >>>>> Many extentions to the periodic task model are possible, including >>>>> things like average runtime with bursts etc.. all have their trade-offs. >>>> >>>> Was that maybe proposed somewhere on LKML (the other models)? >>> >>> RT literatur mostly methinks. Replacing WCET with a statistical model of >>> sorts is not uncommon, the argument goes that not everybody will have >>> their worst case at the same time and lows and highs can commonly cancel >>> out and this way we can cram a little more on the system. >>> >>> Typically this is proposed in the context of soft-realtime systems. >> >> Thanks Peter, I will dive into some books... > > I would look at academic papers, not sure any of that ever made it to > books, Daniel would know I suppose. Good hint, thanks!