linux-kernel - Re: [PATCH V2 6/7] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver

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Date:   Sun, 25 Feb 2018 00:01:08 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Eduardo Valentin <edubezval@...il.com>,
        Kevin Wangtao <kevin.wangtao@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Amit Kachhap <amit.kachhap@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH V2 6/7] thermal/drivers/cpu_cooling: Introduce the cpu
 idle cooling driver

On 23/02/2018 16:26, Vincent Guittot wrote:
> Hi Daniel,
> 
> On 21 February 2018 at 16:29, Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
>> +
>> +/**
>> + * struct cpuidle_cooling_device - data for the idle cooling device
>> + * @cdev: a pointer to a struct thermal_cooling_device
>> + * @cpumask: a cpumask containing the CPU managed by the cooling device
>> + * @timer: a hrtimer giving the tempo for the idle injection cycles
>> + * @kref: a kernel refcount on this structure
>> + * @count: an atomic to keep track of the last task exiting the idle cycle
>> + * @idle_cycle: an integer defining the duration of the idle injection
>> + * @state: an normalized integer giving the state of the cooling device
>> + */
>> +struct cpuidle_cooling_device {
>> +       struct thermal_cooling_device *cdev;
>> +       struct cpumask *cpumask;
>> +       struct list_head node;
>> +       struct hrtimer timer;
>> +       struct kref kref;
>> +       atomic_t count;
>> +       unsigned int idle_cycle;
>> +       unsigned int state;
>> +};
>> +
>> +/**
>> + * @tsk: an array of pointer to the idle injection tasks
>> + * @waitq: the waiq for the idle injection tasks
>> + */
>> +struct cpuidle_cooling_tsk {
>> +       struct task_struct *tsk;
>> +       wait_queue_head_t waitq;
> 
> Why are you creating one wait_queue_head_t per cpu instead of one per
> cooling device and then save a pointer in the per cpu struct
> cpuidle_cooling_tsk ?
> Then, you can use wake_up_interruptible_all() to wake up all threads
> instead of using for_each_cpu ... wake_up_process() loop in
> cpuidle_cooling_wakeup() ?
Yes, that should do the trick. I will give it a try.



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