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 9B682EC873D for ; Thu, 7 Sep 2023 15:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344637AbjIGPdc (ORCPT ); Thu, 7 Sep 2023 11:33:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344004AbjIGPcN (ORCPT ); Thu, 7 Sep 2023 11:32:13 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 140D01FDE; Thu, 7 Sep 2023 08:31:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=SJPILCabtzPOmn/vTtUAzt4xxDqr2K6S5moya2vKXFc=; b=M5Md0zitEkbRpUQMRmi0eh00Qv 7T+cvtivl2P84nn/h8L/APTva0274xldIcRDx4C0Ol8ZbN/xp7nKr2YN5B7IKdUKZ9p3sv33XWpaj P/qg6CT5ArDW4xcAWrkw85DDpDXzgNjAiSbSVvyDT8qV/kPEKNyYQDpv9UIMdpFp7uEkMd930dLZn mzyVrHJaoYWLyZU7gantVtqG64lScf2yjq1CVcJv5ma7f7wYvOzKENyFuHaa/qtn6DFyho1KrEE/t RldIRW0EWiAWLcFuFsgXyINqSRs3KuWiElIVtSgMxKq3jW/UNgjDBNePmWYCSnC9BVxbKEl617hcj S7yAUaAg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qeFDT-001oun-33; Thu, 07 Sep 2023 13:38:42 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0DCDB300687; Thu, 7 Sep 2023 15:38:41 +0200 (CEST) Date: Thu, 7 Sep 2023 15:38:40 +0200 From: Peter Zijlstra To: Lukasz Luba 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 Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Message-ID: <20230907133840.GH10955@noisy.programming.kicks-ass.net> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5616e50d-b827-4547-5b16-9131ace98419@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.