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=-3.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_NEOMUTT autolearn=ham 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 CFEF4C43381 for ; Tue, 5 Mar 2019 16:12:19 +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 9F36B20449 for ; Tue, 5 Mar 2019 16:12:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="j0pJtlkP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F36B20449 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: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=I5I+YbiIcU6RS5d+1z048QSwyjX3oQ4roLlMjQsg3Gw=; b=j0pJtlkPsRdGPk RBqNwvBV2xfDCBjeqayJ8xg1IaGz+5Ipq4Bd/8NcfwSFMnC0KMRmvsMg+XddtkN9yf/mNwd0w/RNJ Ig6xYw7P3/bDSZFNvHCZ6F2uTXV6dM6quZ7fBalUArOWvTRRz5lheHyPm9XrqVo19hW7X2LL+N5PE 4F6hqXmyGSCaA5DjgT69LyN0DcGPxzJf6+rG1e8Zi2dPU+Gbh4z0nn7JV01tUow5Y2D22wwlJEOSZ tNgzQywZNKPNvy1YlSyBf13W9xVp8Bvugs/pzGpUsKNvvE89wTN5qkfXjj5ecpXE8yU1AC6ikHxyB mATyGF3ve2PXUKjXrG/A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1Cfv-0001f2-Ac; Tue, 05 Mar 2019 16:12:15 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1Cfr-0001aX-JL for linux-arm-kernel@lists.infradead.org; Tue, 05 Mar 2019 16:12:13 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C5C94EBD; Tue, 5 Mar 2019 08:12:10 -0800 (PST) Received: from queper01-lin (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4C43F3F703; Tue, 5 Mar 2019 08:12:09 -0800 (PST) Date: Tue, 5 Mar 2019 16:12:03 +0000 From: Quentin Perret To: Chandra Sekhar Lingutla Subject: Re: [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster Message-ID: <20190305161201.rccb6e43wv7ugyxs@queper01-lin> References: <20190228121901.GA26207@e107155-lin> <6d7eb7cc-2453-3a7b-9163-ef9a5389220f@codeaurora.org> <20190228152555.GA13165@e107155-lin> <5785fd91-3d76-78e6-f4c5-7ed07be1a14d@codeaurora.org> <20190304182138.GA7553@e107155-lin> <20190305092322.q7odi3inofnvzhre@queper01-lin> <20190305111321.GA5458@e107155-lin> <20190305112952.zux4bafbnhgnyvlh@queper01-lin> <20190305113633.GA2066@e107155-lin> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171215 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190305_081211_930889_2BB20938 X-CRM114-Status: GOOD ( 23.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: catalin.marinas@arm.com, will.deacon@arm.com, Jeremy Linton , dietmar.eggemann@arm.com, Sudeep Holla , Morten Rasmussen , 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+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tuesday 05 Mar 2019 at 21:23:24 (+0530), Chandra Sekhar Lingutla wrote: > > > On 3/5/2019 5:06 PM, Sudeep Holla wrote: > > On Tue, Mar 05, 2019 at 11:29:55AM +0000, Quentin Perret wrote: > >> On Tuesday 05 Mar 2019 at 11:13:21 (+0000), Sudeep Holla wrote: > >> [...] > >>> While I like the idea, I am afraid that linking this to cpufreq policy > >>> may not be good. How will we deal with it on systems without CPUfreq ? > >> > >> Maybe something like this ? > >> > >> policy = cpufreq_cpu_get(cpu); > >> if (policy) { > >> for_each_cpu(i, policy->related_cpus) { > >> /* Update capacity for @i*/ > >> } > >> cpufreq_cpu_put(policy); > >> } else { > >> /* Update capacity for @cpu*/ > >> } > >> > >> I think it's OK to assume per-cpu capacities w/o CPUFreq. The only > >> case where it makes sense to 'bind' the capacity of several CPUs > >> together is when they're part of the same perf domain, I think. If you > >> don't know what the perf domains are, then there's nothing sensible you > >> can do. > >> > > > > Makes sense. > > > >> And for the dependency, a large part of the arch_topology driver is > >> already dependent on CPUFreq -- it registers a CPUFreq notifier on boot > >> to re-scale the CPU capacities depending on the max freq of the various > >> policies and so on. So the dependency is already there somehow. > >> > > > > Sorry when I mentioned dependency, I meant absence of it needs to be > > dealt with. Your suggestion looks good. > > > >> [...] > >> > >>> I think if there are no valid users of this, we *must* remove it. As I > >>> have pointed out in past, giving user such access will need platform > >>> knowledge. Though it's debatable topic, firmware providing this > >>> information is the only correct solution IMO. > >> > >> Yeah, if nobody is using it then maybe we can just remove it. Or at > >> least we can give it a go and if somebody complains then we can 'fix' it > >> with something like my snippet above :-) > >> > > > > Happy to Ack code removing it ;). The argument that it can't be provided > > by firmware is no longer valid. We already have some dependency on DVFS > > data from the firmware for this to be functional correctly. > > > If at all nobody uses it, making it as read-only (under debugfs) would be good ? I'd say keep the sysfs, but make it RO. I'm aware of a few tools reading from that sysfs node so let's not break them. (None of these tools _write_ in there, though.) > or else we are ok to update patch with related_cpus ? And that we can keep as a backup solution if the above fails. Please also don't forget to CC Greg KH who maintains that file. Thanks, Quentin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel