From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org A292E60555 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752136AbeFFP36 (ORCPT + 25 others); Wed, 6 Jun 2018 11:29:58 -0400 Received: from foss.arm.com ([217.140.101.70]:42004 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955AbeFFP35 (ORCPT ); Wed, 6 Jun 2018 11:29:57 -0400 Date: Wed, 6 Jun 2018 16:29:51 +0100 From: Quentin Perret To: Juri Lelli Cc: Dietmar Eggemann , peterz@infradead.org, rjw@rjwysocki.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.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, pkondeti@codeaurora.org, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org Subject: Re: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management framework Message-ID: <20180606152950.GH10870@e108498-lin.cambridge.arm.com> References: <20180521142505.6522-1-quentin.perret@arm.com> <20180521142505.6522-4-quentin.perret@arm.com> <20180606143739.GF10870@e108498-lin.cambridge.arm.com> <20180606152000.GB15894@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180606152000.GB15894@localhost.localdomain> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 06 Jun 2018 at 17:20:00 (+0200), Juri Lelli wrote: > > > This brings me to another question. Let's say there are multiple users of > > > the Energy Model in the system. Shouldn't the units of frequency and power > > > not standardized, maybe Mhz and mW? > > > The task scheduler doesn't care since it is only interested in power diffs > > > but other user might do. > > > > So the good thing about specifying units is that we can probably assume > > ranges on the values. If the power is in mW, assuming that we're talking > > about a single CPU, it'll probably fit in 16 bits. 65W/core should be > > a reasonable upper-bound ? > > But there are also vendors who might not be happy with disclosing absolute > > values ... These are sometimes considered sensitive and only relative > > numbers are discussed publicly. Now, you can also argue that we already > > have units specified in IPA for ex, and that it doesn't really matter if > > a driver "lies" about the real value, as long as the ratios are correct. > > And I guess that anyone can do measurement on the hardware and get those > > values anyway. So specifying a unit (mW) for the power is probably a > > good idea. > > Mmm, I remember we fought quite a bit while getting capacity-dmpis-mhz > binding accepted, and one of the musts was that the values were going to > be normalized. So, normalized power values again maybe? Hmmm, that's a very good point ... There should be no problems on the scheduler side -- we're only interested in correct ratios. But I'm not sure on the thermal side ... I will double check that. Javi, Viresh, Eduardo: any thoughts about this ? Thanks ! Quentin