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=-5.3 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 14129C433E0 for ; Fri, 19 Feb 2021 09:45:59 +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 B23CC64E28 for ; Fri, 19 Feb 2021 09:45:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B23CC64E28 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=QR7FiA4InAStNiXR5rZnBU04w9VsiHUIzpIXoQfeCqo=; b=A0zbyyIv0g+5V3LKggJF37Kfi w0+JDdbcCA+QKhdplhvqN2WuL7vcu75rx3a39IzujLGsA3CI7lj9d7vm3tXlBZ6Q/bPa5Lt+nqEzk vAUuIpLtEgBbcMSEtz+B2Q1oKJF5pF02J9qxiccOGgZ5Gl6gbW2J/4e1fGVFHBoGPPMyEz0EFCjrN YSinncksowZF212hP361vSTFI6Hxz6iB8vvpe690Lf+1SyjzI2Z/y+mj2YUzqZiwUAPaMNVI8g9Cz ttKcKlLV2sTdxR/aiiVrJFiEGM6kf4557Do7bOEyJF3qqsYYNGm9WKz6Qu5ZSJg10xo14I/PN934U S9nMnZ9Lg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lD2LB-0004Yv-4P; Fri, 19 Feb 2021 09:44:49 +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 1lD2L7-0004YO-L5 for linux-arm-kernel@lists.infradead.org; Fri, 19 Feb 2021 09:44:46 +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 CA595D6E; Fri, 19 Feb 2021 01:44:42 -0800 (PST) Received: from localhost (unknown [10.1.195.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 686C13F694; Fri, 19 Feb 2021 01:44:42 -0800 (PST) Date: Fri, 19 Feb 2021 09:44:40 +0000 From: Ionela Voinescu To: Viresh Kumar Subject: Re: [PATCH V3 1/2] topology: Allow multiple entities to provide sched_freq_tick() callback Message-ID: <20210219094440.GA29843@arm.com> References: <20210203114521.GA6380@arm.com> <20210205091424.3od3tme3f7mh7ebp@vireshk-i7> <20210217002422.GA17422@arm.com> <20210218093304.3mt3o7kbeymn5ofl@vireshk-i7> <20210218163635.GA23622@arm.com> <20210219045823.beeijwaymd63prk7@vireshk-i7> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210219045823.beeijwaymd63prk7@vireshk-i7> 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-20210219_044445_831927_A64CCC68 X-CRM114-Status: GOOD ( 22.36 ) 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: Vincent Guittot , linux-pm@vger.kernel.org, Catalin Marinas , Rafael Wysocki , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Sudeep Holla , Will Deacon , linux-arm-kernel@lists.infradead.org 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 On Friday 19 Feb 2021 at 10:28:23 (+0530), Viresh Kumar wrote: > On 18-02-21, 16:36, Ionela Voinescu wrote: > > Yes, we don't care if there is no cpufreq driver, as the use of AMUs won't > > get initialised either. But we do care if there is a cpufreq driver that > > does not support frequency invariance, which is the example above. > > > > The intention with the patches that made cpufreq based invariance generic > > a while back was for it to be present, seamlessly, for as many drivers as > > possible, as a less than accurate invariance default method is still > > better than nothing. > > Right. > > > So only a few drivers today don't support cpufreq based FI > > Only two AFAICT, both x86, and the AMU stuff doesn't conflict with > them. > > drivers/cpufreq/intel_pstate.c > drivers/cpufreq/longrun.c > > > but it's not a guarantee that it will stay this way. > > What do you mean by "no guarantee" here ? > > The very core routines (cpufreq_freq_transition_end() and > cpufreq_driver_fast_switch()) of the cpufreq core call > arch_set_freq_scale() today and this isn't going to change anytime > soon. If something gets changed there someone will need to see other > parts of the kernel which may get broken with that. > Yes, but it won't really be straightforward to notice this breakage if that happens, so in my opinion it was worth to keep that condition. > I don't see any need of complicating other parts of the kernel like, > amu or cppc code for that. They should be kept simple and they should > assume cpufreq invariance will be supported as it is today. > Fair enough! It is a corner case after all. Thanks, Ionela. > -- > viresh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel