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=-2.2 required=3.0 tests=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 20B87C432C0 for ; Wed, 27 Nov 2019 14:59:03 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E67D220656 for ; Wed, 27 Nov 2019 14:59:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="eMUwN5KN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E67D220656 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.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:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=9nvlI0iyvvTbwWePkWJmZ/HTWL9vX0A3QLEcW8DFnZY=; b=eMUwN5KNL6QgBZ OaOS2FdmDtWE36SmQTz89uTcGuVwsOPttem1zndlM+m/1DS0rYigzsx/P+xnv73QF8IiRseyVbi+3 6ZltYuLZR9yNZq0bQaYzuNBEtmi41X+LVcN2Gl+xkjH0ZrauH7TkWrh+a+y2RuDTV9saJ0G0tnG4H vF8hu849vwujxefwcX72HuwBzyBcSunOPs/uO0Vg5kE9thn0prHUKThNk5LsnA2QtLuRva9rTVWol oPBAev2ZWU6m1NE+hndhoxt09xd005QNynz9n+hnI3x1RxVZv2kRio+9LJcI8KQdUOebHkP14A4IW 2YBnydPHkIzodnSJi2pw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iZymQ-000488-NF; Wed, 27 Nov 2019 14:58:58 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iZymN-00047j-9I for linux-arm-kernel@lists.infradead.org; Wed, 27 Nov 2019 14:58:56 +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 A22E430E; Wed, 27 Nov 2019 06:58:52 -0800 (PST) Received: from [192.168.0.9] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 268D63F68E; Wed, 27 Nov 2019 06:58:51 -0800 (PST) Subject: Re: [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of policy->related_cpus during CPU hp To: Sudeep Holla , Viresh Kumar References: <20191127114801.23837-1-dietmar.eggemann@arm.com> <20191127120816.GC29301@bogus> <20191127121402.vd3tul4gmqm6qtyb@vireshk-i7> <20191127133200.GE29301@bogus> From: Dietmar Eggemann Message-ID: Date: Wed, 27 Nov 2019 15:58:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <20191127133200.GE29301@bogus> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191127_065855_379876_BED2AAC8 X-CRM114-Status: GOOD ( 15.27 ) 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: Lorenzo Pieralisi , linux-pm@vger.kernel.org, "Rafael J . Wysocki" , Liviu Dudau , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Morten Rasmussen , Lukasz Luba Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 27/11/2019 14:32, Sudeep Holla wrote: > On Wed, Nov 27, 2019 at 05:44:02PM +0530, Viresh Kumar wrote: >> On 27-11-19, 12:08, Sudeep Holla wrote: >>> On Wed, Nov 27, 2019 at 12:48:01PM +0100, Dietmar Eggemann wrote: [...] >>> Unlike DT based drivers, it not easy to get the fixed cpumask unless we >>> add some mechanism to extract it based on clks/OPP added. I prefer >>> this simple solution instead. >> >> I will call this a work-around for the problem and not really the >> solution, though I won't necessarily oppose it. There are cases which >> will break even with this solution. >> > > I agree and that's the reason I spoke out my thought aloud here :) > >> - Boot board with cpufreq driver as module. >> - Offline all CPUs except CPU0. >> - insert cpufreq driver. >> - online all CPUs. >> > > Indeed, not just boot anytime since it's a module :) > >> Now there is no guarantee that the last online will get the mask >> properly, if I have understood the problem well :) >> > > Yes > >> But yeah, who does this kind of messy work anyway :) >> > > I won't bet on that ;) > >> FWIW, we need a proper way (may be from architecture code) to find >> list of all CPUs that share clock line. >> > > Yes but there's no architectural way. I need to revise and see tc2_pm.c > to check if we can do any magic there. I'm fine with finding a better solution to return a fixed topology core cpumask or calling this patch a workaround. AFAICS, only TC2 is affected. ("arm: Fix topology setup in case of CPU hotplug for CONFIG_SCHED_MC") is needed for other systems as well in case we have commit ca74b316df96 ("arm: Use common cpu_topology structure and functions."). We probably don't want to revert commit ca74b316df96? We do CPU hp stress tests in our EAS mainline integration test suite https://developer.arm.com/tools-and-software/open-source-software/linux-kernel/energy-aware-scheduling/eas-mainline-development and there is where we initially encountered this issue on TC2. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel