From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751223AbdE2JUh (ORCPT ); Mon, 29 May 2017 05:20:37 -0400 Received: from foss.arm.com ([217.140.101.70]:47176 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbdE2JUf (ORCPT ); Mon, 29 May 2017 05:20:35 -0400 Subject: Re: [PATCH v4 8/8] arm,arm64,drivers: add a prefix to drivers arch_topology interfaces To: Greg KH , Juri Lelli Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com, linux@arm.linux.org.uk, sudeep.holla@arm.com, lorenzo.pieralisi@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, morten.rasmussen@arm.com, broonie@kernel.org References: <20170420144316.15632-1-juri.lelli@arm.com> <20170420144316.15632-9-juri.lelli@arm.com> <20170525131802.GE16244@kroah.com> <20170526101032.2t2xn5wrfenimu5w@e106622-lin> <20170526183610.GB16490@kroah.com> From: Dietmar Eggemann Message-ID: Date: Mon, 29 May 2017 11:20:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170526183610.GB16490@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, On 05/26/2017 08:36 PM, Greg KH wrote: > On Fri, May 26, 2017 at 11:10:32AM +0100, Juri Lelli wrote: >> Hi, >> >> On 25/05/17 15:18, Greg KH wrote: >>> On Thu, Apr 20, 2017 at 03:43:16PM +0100, Juri Lelli wrote: [...] >>> But this is all really topology stuff, right? Why use "capacity" at >>> all: >>> topology_normalize_cpu() >>> topology_parse_cpu() >>> topology_scale_cpu() >>> topology_set_scale() >>> ? >>> >>> It's always best to put the "subsystem" name first, we have a bad >>> history of getting this wrong in the past by putting the verb first, not >>> the noun. >>> >> >> topology_ works for me. However, I'd keep "capacity" in the names, as we >> might need to topology_normalize_cpu_somethingelse() (etc.) in the >> future? > > Worry about the future, in the future. Change the names then, _IF_ it > becomes an issue. Try to be short and simple please. > >> Updated patch follows. I kept Catalin and Russell's acks as I only >> renamed the functions, please shout if that's not OK. >> >> Greg, if you are fine with this approach, do you still want a complete >> v5 of the set or can you pick this up? > > Am I the one who is supposed to take all of these arm-specific patches? > If so, that's fine, but I need to have acks from the arm maintainers... > > Oh, and drop "capacity" please :) Once we have driver/base/arch_topology.c in, we want to enable (cpu micro-architectural + max frequency (OPPmax)) invariant and frequency (OPPmin..OPPmax) invariant load-tracking/accounting in the task scheduler for arm and arm64. The way to do this is to define the task scheduler interfaces arch_scale_cpu_capacity() and arch_scale_freq_capacity() in arch specific code: #define arch_scale_cpu_capacity topology_scale_cpu_capacity #define arch_scale_freq_capacity topology_scale_freq_capacity In case an arch is not defining them, the default definitions in kernel/sched/sched.h are used. So topology_scale_cpu() wouldn't be correct since we scale the _capacity_ by the micro-architectural differences (hence cpu) and not the cpu. Likewise we will have a function topology_scale_freq_capacity indicating that we scale the capacity by the frequency. Or would you prefer something like topology_scale_capacity_by_cpu() and topology_scale_capacity_by_freq()? -- Dietmar [...]