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=-5.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 03E57C55178 for ; Thu, 5 Nov 2020 15:47:42 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F621206FA for ; Thu, 5 Nov 2020 15:47:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="S+xweyhL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F621206FA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=d2QO4Kd3s4CyrYMhiyRdFQu+PnwWfPOw2pqtuxnhiCg=; b=S+xweyhLn1bdy0qImoE4AkNXp cdFsDTACXFEqonRGOaLGx2r5ZFWe/OtZAe3395XjvzajTsmTwSCEqeTxFm6zpAnyLOAXT67GPHNDO tSGVOkTB3HmWvPDL1OaMWvs+uRoQngsgYjjfbwnirQm894dWW/6B8LO+F/gY0kCiEk0yXEfOQjNe0 EEZO4PoTy6Qc8kW7lu8u4GCk8+pNyD4Mq+v+6zsEbP/HSCVB0iFLSfPPSALxcHsVZzDdb/LocNoCV cRdUTrle4xqEIWvaPrMSu04Bi4LnoqvjWGuHvoKsVo/SUZIXdCvL1/qLRdCiLlwFIy+leb6v4p0UL 5iHO2rqUQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kahSu-0007pd-Bw; Thu, 05 Nov 2020 15:46:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kahSr-0007p0-59 for linux-arm-kernel@lists.infradead.org; Thu, 05 Nov 2020 15:46:18 +0000 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 8A71C14BF; Thu, 5 Nov 2020 07:46:14 -0800 (PST) Received: from localhost (unknown [10.1.198.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1CA483F718; Thu, 5 Nov 2020 07:46:14 -0800 (PST) Date: Thu, 5 Nov 2020 15:46:12 +0000 From: Ionela Voinescu To: Vincent Guittot Subject: Re: [PATCH v3 0/3] CPUFreq: Add support for cpu performance dependencies Message-ID: <20201105154612.GA17891@arm.com> References: <20201102120115.29993-1-nicola.mazzucato@arm.com> <20201103101840.yrgwmcjrnjn7n5q6@vireshk-i7> <87558fa9-a4c6-38c9-bcc5-f736c0229f56@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201105_104617_306496_44227405 X-CRM114-Status: GOOD ( 27.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nishanth Menon , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "open list:THERMAL" , Stephen Boyd , Viresh Kumar , Daniel Lezcano , "Rafael J. Wysocki" , linux-kernel , Rob Herring , Nicola Mazzucato , Sudeep Holla , Chris Redpath , Morten Rasmussen , LAK , Viresh Kumar Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi guys, On Thursday 05 Nov 2020 at 15:25:53 (+0100), Vincent Guittot wrote: [..] > > > - Because of hardware co-ordination of otherwise co-ordinated CPUs, > > > few things break. Thermal and EAS are some of the examples and so > > > you are trying to fix them here by proving them the missing > > > information again. > > > > Correct. And for this I have proposed two ways. > > > > > > > > - One other thing that breaks with this is freq-invariance in the > > > scheduler, as the scheduler won't see the real frequencies the > > > various CPUs are running at. Most of the hardware we have today > > > doesn't have counters, like AMUs, not sure if all future ones based > > > on SCMI will have that too, so how are they gong to be fixed ? > > > > > > > Correct. freq-invariance without counters is trying to do its best based on the > > information it has available. It definitely relies on the knowledge of the v/f > > domains to work at its best so I think in the case of per-cpu it will follow the > > same approach as others being affected (EAS, thermal). > > As frequency invariance has same problem as EAS and Thermal it would > be good to see the solution as part of this proposal like EAS and > Thermal > I think I was waiting for a consensus on patch 3/3, although I believe the discussion at [1] tended towards option 2: "each driver to store internally the performance dependencies and let the driver directly provide the correct cpumask for any consumer." The alternative was option 1: "add a new dependent_cpus cpumaks in cpufreq_policy", as Nicola mentioned in the commit message for 3/3. If the choice is clear, I'm happy to take the FIE fixes in a separate set. Thanks, Ionela. [1] https://lore.kernel.org/linux-arm-kernel/20200924095347.32148-3-nicola.mazzucato@arm.com/ > > > > > And if we even have to fix this (freq invariance), what's hardware > > > coordination giving us that makes all this worth it ? > > > > I suppose this is more a generic question for all the platforms running with h/w > > coordination, but for our case is that the f/w will take care of the performance > > optimizations for us :) > > > > > > > > Sorry about the long list :) > > > > No problem at all. Thank you for your time on this and I hope I have made bits > > clearer. > > > > Nicola > > > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel