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 ACCA3C4167B for ; Tue, 5 Dec 2023 15:19:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346068AbjLEPS5 (ORCPT ); Tue, 5 Dec 2023 10:18:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346031AbjLEPSz (ORCPT ); Tue, 5 Dec 2023 10:18:55 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 62864A9 for ; Tue, 5 Dec 2023 07:19:02 -0800 (PST) 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 AED3E139F; Tue, 5 Dec 2023 07:19:48 -0800 (PST) Received: from [10.1.31.59] (e133649.arm.com [10.1.31.59]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 376D23F6C4; Tue, 5 Dec 2023 07:19:00 -0800 (PST) Message-ID: Date: Tue, 5 Dec 2023 15:18:58 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/6] sched: uclamp sum aggregation Content-Language: en-US To: Vincent Guittot Cc: Qais Yousef , Ingo Molnar , Peter Zijlstra , Dietmar Eggemann , Morten Rasmussen , Lukasz Luba , Christian Loehle , linux-kernel@vger.kernel.org References: <20231203002544.d4zx3oyvjugohh22@airbuntu> <7f1f7dd0-e3b5-4e16-a44e-c08fca567f97@arm.com> From: Hongyan Xia In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/12/2023 16:12, Vincent Guittot wrote: > On Mon, 4 Dec 2023 at 02:48, Hongyan Xia wrote: >> >> [...] >> >> Other shortcomings are not that critical, but the fact that uclamp_min's >> effectiveness is divided by N under max aggregation I think is not >> acceptable. > > Change EAS task placement policy in this case to take into account > actual utilization and uclamp_min/max Thank you. I agree. I want to emphasize this specifically because this is exactly what I'm trying to do. The whole series can be rephrased in a different way: - The PELT signal is distorted when uclamp is active. - Let's consider the [PELT, uclamp_min, uclamp_max] tuple. - Always carrying all three variables is too much, but [PELT, clamped(PELT)] is an approximation that works really well. Of course, I'll explore if there's a way to make things less messy. I just realized why I didn't do things util_est way but instead directly clamping on PELT, it's because util_est boosts util_avg and can't work for uclamp_max. I'll keep exploring options. >> [...]