Messages in this thread | | | Subject | Re: [PATCH 5/8] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver | From | Daniel Lezcano <> | Date | Wed, 31 Jan 2018 16:27:44 +0100 |
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On 31/01/2018 10:56, Vincent Guittot wrote: > On 31 January 2018 at 10:50, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >> On 31/01/2018 10:46, Vincent Guittot wrote: >>> On 31 January 2018 at 10:33, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: >>>> On 31/01/2018 10:01, Vincent Guittot wrote: >>>>> Hi Daniel, >>>>> >>>>> On 23 January 2018 at 16:34, Daniel Lezcano <daniel.lezcano@linaro.org> 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; };
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