From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932206AbeAaP1w (ORCPT ); Wed, 31 Jan 2018 10:27:52 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:53164 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbeAaP1s (ORCPT ); Wed, 31 Jan 2018 10:27:48 -0500 X-Google-Smtp-Source: AH8x224CMdHKBiFhtqZYx5WZaM3YgaCs32ESDgzH+3SF6OOyw8tVuiYIRqJJE+u73RKBJx1xiqtz4Q== Subject: Re: [PATCH 5/8] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver To: Vincent Guittot Cc: Eduardo Valentin , Kevin Wangtao , Leo Yan , Amit Kachhap , viresh kumar , linux-kernel , Zhang Rui , Javi Merino , "open list:THERMAL" References: <1516721671-16360-1-git-send-email-daniel.lezcano@linaro.org> <1516721671-16360-6-git-send-email-daniel.lezcano@linaro.org> <11334876-ef8c-58fa-5e32-ab8499eebd7e@linaro.org> <6e776e6c-6f1e-b33b-58b7-b95410ca1f95@linaro.org> From: Daniel Lezcano Message-ID: <22f4c4fc-fd74-b635-6859-7e2f599695f7@linaro.org> Date: Wed, 31 Jan 2018 16:27:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/01/2018 10:56, Vincent Guittot wrote: > On 31 January 2018 at 10:50, Daniel Lezcano wrote: >> On 31/01/2018 10:46, Vincent Guittot wrote: >>> On 31 January 2018 at 10:33, Daniel Lezcano wrote: >>>> On 31/01/2018 10:01, Vincent Guittot wrote: >>>>> Hi Daniel, >>>>> >>>>> On 23 January 2018 at 16:34, Daniel Lezcano wrote: >>>> >>>> [ ... ] (please trim :) >>>> >>>>>> + /* >>>>>> + * Each cooling device is per package. Each package >>>>>> + * has a set of cpus where the physical number is >>>>>> + * duplicate in the kernel namespace. We need a way to >>>>>> + * address the waitq[] and tsk[] arrays with index >>>>>> + * which are not Linux cpu numbered. >>>>>> + * >>>>>> + * One solution is to use the >>>>>> + * topology_core_id(cpu). Other solution is to use the >>>>>> + * modulo. >>>>>> + * >>>>>> + * eg. 2 x cluster - 4 cores. >>>>>> + * >>>>>> + * Physical numbering -> Linux numbering -> % nr_cpus >>>>>> + * >>>>>> + * Pkg0 - Cpu0 -> 0 -> 0 >>>>>> + * Pkg0 - Cpu1 -> 1 -> 1 >>>>>> + * Pkg0 - Cpu2 -> 2 -> 2 >>>>>> + * Pkg0 - Cpu3 -> 3 -> 3 >>>>>> + * >>>>>> + * Pkg1 - Cpu0 -> 4 -> 0 >>>>>> + * Pkg1 - Cpu1 -> 5 -> 1 >>>>>> + * Pkg1 - Cpu2 -> 6 -> 2 >>>>>> + * Pkg1 - Cpu3 -> 7 -> 3 >>>>> >>>>> >>>>> I'm not sure that the assumption above for the CPU numbering is safe. >>>>> Can't you use a per cpu structure to point to resources that are per >>>>> cpu instead ? so you will not have to rely on CPU ordering >>>> >>>> Can you elaborate ? I don't get the part with the percpu structure. >>> >>> Something like: >>> >>> struct cpuidle_cooling_cpu { >>> struct task_struct *tsk; >>> wait_queue_head_t waitq; >>> }; >>> >>> DECLARE_PER_CPU(struct cpuidle_cooling_cpu *, cpu_data); >> >> I got this part but I don't get how that fixes the ordering thing. > > Because you don't care of the CPU ordering to retrieve the data as > they are stored per cpu directly That's what I did initially, but for consistency reasons with the cpufreq cpu cooling device which is stored in a list and the combo cpu cooling device, the cpuidle cooling device must be per cluster and stored in a list. Alternatively I can do: struct cpuidle_cooling_device { struct thermal_cooling_device *cdev; - struct task_struct **tsk; + struct task_struct __percpu *tsk; struct cpumask *cpumask; struct list_head node; struct hrtimer timer; struct kref kref; - wait_queue_head_t *waitq; + wait_queue_head_t __percpu waitq; atomic_t count; unsigned int idle_cycle; unsigned int state; }; -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog