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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 8C7D5C433EF for ; Tue, 19 Jun 2018 10:19:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50AED20836 for ; Tue, 19 Jun 2018 10:19:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50AED20836 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757170AbeFSKTH (ORCPT ); Tue, 19 Jun 2018 06:19:07 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:38633 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756548AbeFSKTF (ORCPT ); Tue, 19 Jun 2018 06:19:05 -0400 Received: by mail-wm0-f68.google.com with SMTP id 69-v6so20959872wmf.3 for ; Tue, 19 Jun 2018 03:19:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=PB2EbKXB9DEsvRNJ7ll+FIVhxw6CbwWtN75AQs/yNFQ=; b=GOSYDsUcALlVqMglQOiUs4TFVgJeCgCoBHoSCaQUZStEOF5n0fKHDG/VpppQYnph5f hv6G5pv2yb9z3ceLsqlr4ZXXTvIc8eR0q521gYITMfJmwck9BGd/zNSG6DTUvsUw6Oxz G7SK8sq43Iijht5WjnSqDLO8h9E6dugsG26ci6YsPpDyC0XalXl8dIB1jft7ERuTEp16 yppcke/ZEPkUXJj3Sc4Qb5k8Aw1Wd8vElKTGui+t1yTIqLfpQV+zku5EkZ0cEmyUNMXE DgIFJf37sknvO5PIW6sal9GBIp27FXhwJkqd5JqNWAfZg2RAJNZETV/ECA1k5f5ejH7K lxvw== X-Gm-Message-State: APt69E1qf3uBf36VIoTKYOigmKzZRXRu/6KeeLpzU7LLPo8lj8Jn6/c4 COnsFt18QccmxNYc5fDUlzsLdQ== X-Google-Smtp-Source: ADUXVKIkZzuBckQuO+afgI4hGVqE8bbBn6a4lNCqyXwTacYaPgS9Kin3hkn/I/Ix+Xt7Mc/U2OdNAg== X-Received: by 2002:a1c:c90:: with SMTP id 138-v6mr10673335wmm.110.1529403544759; Tue, 19 Jun 2018 03:19:04 -0700 (PDT) Received: from localhost.localdomain ([151.15.207.242]) by smtp.gmail.com with ESMTPSA id c18-v6sm16211202wrq.17.2018.06.19.03.19.02 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Jun 2018 03:19:04 -0700 (PDT) Date: Tue, 19 Jun 2018 12:19:01 +0200 From: Juri Lelli To: Quentin Perret Cc: Pavan Kondeti , peterz@infradead.org, rjw@rjwysocki.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joelaf@google.com, smuckle@google.com, adharmap@quicinc.com, skannan@quicinc.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org Subject: Re: [RFC PATCH v3 10/10] arch_topology: Start Energy Aware Scheduling Message-ID: <20180619101901.GC13617@localhost.localdomain> References: <20180521142505.6522-1-quentin.perret@arm.com> <20180521142505.6522-11-quentin.perret@arm.com> <20180619091841.GD9208@codeaurora.org> <20180619094002.GR17720@e108498-lin.cambridge.arm.com> <20180619094714.GA13617@localhost.localdomain> <20180619100224.GT17720@e108498-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619100224.GT17720@e108498-lin.cambridge.arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/06/18 11:02, Quentin Perret wrote: > On Tuesday 19 Jun 2018 at 11:47:14 (+0200), Juri Lelli wrote: > > On 19/06/18 10:40, Quentin Perret wrote: > > > Hi Pavan, > > > > > > On Tuesday 19 Jun 2018 at 14:48:41 (+0530), Pavan Kondeti wrote: > > > > [...] > > > > > > There seems to be a sysfs interface exposed by this driver to change cpu_scale. > > > > Should we worry about it? I don't know what is the usecase for changing the > > > > cpu_scale from user space. > > > > > > This is something I've been wondering as well. TBH, I'm not sure what to > > > do in this case. And I'm not sure to know what is the use-case either. > > > Debugging purpose I assume ? > > > > > > Juri, did you have a specific use-case for this feature when the > > > arch_topology driver was first introduced ? Or was it just to align > > > with the existing arm/arm64 code ? > > > > It was requested (IIRC) because DT might have bogus values and not be > > easily modifiable. So, this is another way to get things right for your > > platform at runtime. > > Right, but that also allows you to set different capacities to CPUs > inside the same freq domain, which isn't supported by the EM framework, > at least for now. So I would prefer to assume that your values in DT must > to be correct to use EAS, and leave the code as-is for now. It's actually built on the (current) assumption that siblings share capacity [1], so it seems to align with what EM requires. [1] https://elixir.bootlin.com/linux/latest/source/drivers/base/arch_topology.c#L71