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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 080B8C43381 for ; Wed, 6 Mar 2019 09:48:59 +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 CE52B20661 for ; Wed, 6 Mar 2019 09:48:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PR7C7Lbi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE52B20661 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-Type: Content-Transfer-Encoding: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=Isj2JcTesHhBKu3AhIhN+ahmXFigjP+tyxiVNRnJ9TQ=; b=PR7C7LbiUA6LFQVCJaU2m7PUr bjKd+yg6KTKObLVbqnVJjRVBr71J8s/WIeK1FezXM6VZ4IFPaZVRCKFaiPsWPg2l7oW3MFLMlcmW6 y/SkHCRPKfqkRnsTszj9HRBaacorMLk/nx+f8fbjb4TdFB9Er51iLvEXFgf31UcKXRGKgHaPAVV/Y I0LYREXAZnZauSvfPC/cIgcjsVKWA4pgDaYRrNJEF3Ef52uHdF9UrUlGz7eFOSjwWaUODIMAv7HBL OXH3pFvy9na2blpdtYnBHTnNuiqqyakj3AEoRWuq2G2rOd4SPqbzsXnUbjICwolxTbnOWfrMpojk4 VHlHshS9g==; 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 1h1TAV-0001td-Me; Wed, 06 Mar 2019 09:48:55 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1TAO-0001g2-0u for linux-arm-kernel@lists.infradead.org; Wed, 06 Mar 2019 09:48:52 +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 04766A78; Wed, 6 Mar 2019 01:48:45 -0800 (PST) Received: from [0.0.0.0] (e107985-lin.cambridge.arm.com [10.1.194.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 39A483F71D; Wed, 6 Mar 2019 01:48:43 -0800 (PST) Subject: Re: [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster To: Quentin Perret , Sudeep Holla References: <1551354838-29902-1-git-send-email-clingutla@codeaurora.org> <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> From: Dietmar Eggemann Message-ID: Date: Wed, 6 Mar 2019 10:48:41 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190305112952.zux4bafbnhgnyvlh@queper01-lin> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190306_014848_672739_E2873AA4 X-CRM114-Status: GOOD ( 20.15 ) 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: Chandra Sekhar Lingutla , catalin.marinas@arm.com, will.deacon@arm.com, Jeremy Linton , Morten Rasmussen , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 3/5/19 12:29 PM, 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. > > 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. > > [...] > >> 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 :-) +1 for dropping the write capability for this sysfs. I questioned the usefulness of the interface already in 2015: https://lkml.org/lkml/2015/12/10/324 Now in the meantime, reading the interface for all CPUs became a nice way of figuring out that we're on a system with asymmetric CPU capacities (big.LITTLE or DynamIQ). Especially for systems w/o an Energy Model. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel