From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick Bellasi Subject: Re: [RFC PATCH 1/7] PM: Introduce em_pd_get_higher_freq() Date: Thu, 16 May 2019 14:22:50 +0100 Message-ID: <20190516132250.hedtianse7rnk3wq@e110439-lin> References: <20190508174301.4828-1-douglas.raillard@arm.com> <20190508174301.4828-2-douglas.raillard@arm.com> <20190516124200.opxczohjelhvrzmo@e110439-lin> <20190516130148.uhq55ptut47usnae@queper01-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190516130148.uhq55ptut47usnae@queper01-lin> Sender: linux-kernel-owner@vger.kernel.org To: Quentin Perret Cc: douglas.raillard@arm.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, dietmar.eggemann@arm.com List-Id: linux-pm@vger.kernel.org On 16-May 14:01, Quentin Perret wrote: > On Thursday 16 May 2019 at 13:42:00 (+0100), Patrick Bellasi wrote: > > > +static inline unsigned long em_pd_get_higher_freq(struct em_perf_domain *pd, > > > + unsigned long min_freq, unsigned long cost_margin) > > > +{ > > > + unsigned long max_cost = 0; > > > + struct em_cap_state *cs; > > > + int i; > > > + > > > + if (!pd) > > > + return min_freq; > > > + > > > + /* Compute the maximum allowed cost */ > > > + for (i = 0; i < pd->nr_cap_states; i++) { > > > + cs = &pd->table[i]; > > > + if (cs->frequency >= min_freq) { > > > + max_cost = cs->cost + (cs->cost * cost_margin) / 1024; > > ^^^^ > > ... end here we should probably better use SCHED_CAPACITY_SCALE > > instead of hard-coding in values, isn't it? > > I'm not sure to agree. This isn't part of the scheduler per se, and the > cost thing isn't in units of capacity, but in units of power, so I don't > think SCHED_CAPACITY_SCALE is correct here. Right, I get the units do not match and it would not be elegant to use it here... > But I agree these hard coded values (that one, and the 512 in one of the > following patches) could use some motivation :-) ... ultimately SCHED_CAPACITY_SCALE is just SCHED_FIXEDPOINT_SCALE, which is adimensional. Perhaps we should use that or yet another alias for the same. > Thanks, > Quentin -- #include Patrick Bellasi 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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 B2089C04AAF for ; Thu, 16 May 2019 13:22:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F21E20862 for ; Thu, 16 May 2019 13:22:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727015AbfEPNWy (ORCPT ); Thu, 16 May 2019 09:22:54 -0400 Received: from foss.arm.com ([217.140.101.70]:45662 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726955AbfEPNWy (ORCPT ); Thu, 16 May 2019 09:22:54 -0400 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 708481715; Thu, 16 May 2019 06:22:54 -0700 (PDT) Received: from e110439-lin (e110439-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1A0F53F703; Thu, 16 May 2019 06:22:52 -0700 (PDT) Date: Thu, 16 May 2019 14:22:50 +0100 From: Patrick Bellasi To: Quentin Perret Cc: douglas.raillard@arm.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, dietmar.eggemann@arm.com Subject: Re: [RFC PATCH 1/7] PM: Introduce em_pd_get_higher_freq() Message-ID: <20190516132250.hedtianse7rnk3wq@e110439-lin> References: <20190508174301.4828-1-douglas.raillard@arm.com> <20190508174301.4828-2-douglas.raillard@arm.com> <20190516124200.opxczohjelhvrzmo@e110439-lin> <20190516130148.uhq55ptut47usnae@queper01-lin> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190516130148.uhq55ptut47usnae@queper01-lin> User-Agent: NeoMutt/20180716 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Message-ID: <20190516132250.cERx1xyNd4ScEWdS7-Cn0rpqAYOwf7V3n1ewiFl_dqc@z> On 16-May 14:01, Quentin Perret wrote: > On Thursday 16 May 2019 at 13:42:00 (+0100), Patrick Bellasi wrote: > > > +static inline unsigned long em_pd_get_higher_freq(struct em_perf_domain *pd, > > > + unsigned long min_freq, unsigned long cost_margin) > > > +{ > > > + unsigned long max_cost = 0; > > > + struct em_cap_state *cs; > > > + int i; > > > + > > > + if (!pd) > > > + return min_freq; > > > + > > > + /* Compute the maximum allowed cost */ > > > + for (i = 0; i < pd->nr_cap_states; i++) { > > > + cs = &pd->table[i]; > > > + if (cs->frequency >= min_freq) { > > > + max_cost = cs->cost + (cs->cost * cost_margin) / 1024; > > ^^^^ > > ... end here we should probably better use SCHED_CAPACITY_SCALE > > instead of hard-coding in values, isn't it? > > I'm not sure to agree. This isn't part of the scheduler per se, and the > cost thing isn't in units of capacity, but in units of power, so I don't > think SCHED_CAPACITY_SCALE is correct here. Right, I get the units do not match and it would not be elegant to use it here... > But I agree these hard coded values (that one, and the 512 in one of the > following patches) could use some motivation :-) ... ultimately SCHED_CAPACITY_SCALE is just SCHED_FIXEDPOINT_SCALE, which is adimensional. Perhaps we should use that or yet another alias for the same. > Thanks, > Quentin -- #include Patrick Bellasi