From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH V2 6/7] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver Date: Wed, 4 Apr 2018 10:50:02 +0200 Message-ID: <78504a65-d21a-eea0-d8af-6e12d5747b87@linaro.org> References: <1519226968-19821-1-git-send-email-daniel.lezcano@linaro.org> <1519226968-19821-7-git-send-email-daniel.lezcano@linaro.org> <20180223073432.GF26947@vireshk-i7> <20180226043021.GK26947@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180226043021.GK26947@vireshk-i7> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Viresh Kumar Cc: edubezval@gmail.com, kevin.wangtao@linaro.org, leo.yan@linaro.org, vincent.guittot@linaro.org, amit.kachhap@gmail.com, linux-kernel@vger.kernel.org, javi.merino@kernel.org, rui.zhang@intel.com, daniel.thompson@linaro.org, linux-pm@vger.kernel.org List-Id: linux-pm@vger.kernel.org On 26/02/2018 05:30, Viresh Kumar wrote: [ ... ] >>>> + >>>> + for_each_possible_cpu(cpu) { >>>> + cpumask = topology_core_cpumask(cpu); >>>> + >>>> + cct = per_cpu_ptr(&cpuidle_cooling_tsk, cpu); >>>> + >>>> + /* >>>> + * This condition makes the first cpu belonging to the >>>> + * cluster to create a cooling device and allocates >>>> + * the structure. Others CPUs belonging to the same >>>> + * cluster will just increment the refcount on the >>>> + * cooling device structure and initialize it. >>>> + */ >>>> + if (cpu == cpumask_first(cpumask)) { >>> >>> Your function still have few assumptions of cpu numbering and it will >>> break in few cases. What if the CPUs on a big Little system (4x4) are >>> present in this order: B L L L L B B B ?? >>> >>> This configuration can happen if CPUs in DT are marked as: 0-3 LITTLE, >>> 4-7 big and a big CPU is used by the boot loader to bring up Linux. >> >> Ok, how can I sort it out ? > > I would do something like this: > > cpumask_copy(possible, cpu_possible_mask); > > while (!cpumask_empty(possible)) { > first = cpumask_first(possible); > cpumask = topology_core_cpumask(first); > cpumask_andnot(possible, possible, cpumask); > > allocate_cooling_dev(first); //This is most of this function in your patch. > > while (!cpumask_empty(cpumask)) { > temp = cpumask_first(possible); > //rest init "temp" > cpumask_clear_cpu(temp, cpumask); > } > > //Everything done, register cooling device for cpumask. > } Mmh, that sounds very complex. May be it is simpler to count the number of cluster and initialize the idle_cdev for each cluster and then go for this loop with the cluster cpumask. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog