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 91358EE8006 for ; Fri, 8 Sep 2023 13:58:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231410AbjIHN67 (ORCPT ); Fri, 8 Sep 2023 09:58:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243524AbjIHN64 (ORCPT ); Fri, 8 Sep 2023 09:58:56 -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 CC0A81BF8; Fri, 8 Sep 2023 06:58:50 -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=Wcr8a8tBWINLXI36zvPNSpRI4FGFx++ifjXy4lZNYKw=; b=b2HFnzZX5M+bXCic/fxOccx1Ci 43Q4tIUuOWBjHHRDGWnhVZxwOLkD9bYF+fHvNhiysfxlQvbbnBcCtryXrKAiZsVYXucjQ9OIjkbWp 4MkMaNjM5XEBgiYTMZcgCeG56KSqGbwZYdGOMwsDMy83K8o6oC1XWHYSzsmlw3lDBvP5sLB3AsIjM LaxqhJXD89hPx1LdR24cy5nsGVw2WR/n28FZYHkgntBsK5r/X/x+WDSNdJjs7d8Yl+8XjDAxCEasW xhfR7pLyvZf7VVNfEIh4zzjx1qyKkLA8l00kF50uwjxtC1JrZrmxU2bnWr9ij8mmVe9bFd+jUGH0Y KQ2IqctQ==; 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 1qec0Q-002YU2-2z; Fri, 08 Sep 2023 13:58:44 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0E0F0300472; Fri, 8 Sep 2023 15:58:44 +0200 (CEST) Date: Fri, 8 Sep 2023 15:58:43 +0200 From: Peter Zijlstra To: Qais Yousef Cc: Ingo Molnar , "Rafael J. Wysocki" , Viresh Kumar , Vincent Guittot , Dietmar Eggemann , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Lukasz Luba Subject: Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins Message-ID: <20230908135843.GC24372@noisy.programming.kicks-ass.net> References: <20230827233203.1315953-1-qyousef@layalina.io> <20230907130805.GE10955@noisy.programming.kicks-ass.net> <20230908001725.mtqbse3xwhzvo5qp@airbuntu> <20230908102511.GA24372@noisy.programming.kicks-ass.net> <20230908133336.uge4hcnx4cum3lg5@airbuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230908133336.uge4hcnx4cum3lg5@airbuntu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 08, 2023 at 02:33:36PM +0100, Qais Yousef wrote: > > > UTIL_EST_FASTER moves in one direction. And it's a constant response too, no? > > > > The idea of UTIL_EST_FASTER was that we run a PELT sum on the current > > activation runtime, all runtime since wakeup and take the max of this > > extra sum and the regular thing. > > > > On top of that this extra PELT sum can/has a time multiplier and thus > > ramps up faster (this multiplies could be per task). Nb.: > > > > util_est_fast = faster_est_approx(delta * 2); > > > > is a state-less expression -- by making > > > > util_est_fast = faster_est_approx(delta * curr->se.faster_mult); > > > > only the current task is affected. > > Okay; maybe I didn't understand this fully and will go back and study it more. > > Maybe the word faster is what makes me worried as I really see faster is not > what people want on a class of systems; or at least CPUs if you think of HMP. > Taming the beast is a more difficult problem in this class of systems. The faster refers to the ramp-up. Which was the issue identified in that earlier thread. The game thing wanted to ramp up more agressive.