linux-kernel - Re: [PATCH RFC 1/2] thermal/cpu idle cooling: Introduce cpu idle cooling driver

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Date:   Thu, 8 Jun 2017 15:42:19 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Jean Wangtao <jean.wangtao@...aro.org>
Cc:     edubezval@...il.com, javi.merino@...nel.org,
        viresh kumar <viresh.kumar@...aro.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Tao Wang <kevin.wangtao@...ilicon.com>,
        "Sunzhaosheng Sun(Zhaosheng)" <sunzhaosheng@...ilicon.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Amit Kachhap <amit.kachhap@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>, rui.zhang@...el.com
Subject: Re: [PATCH RFC 1/2] thermal/cpu idle cooling: Introduce cpu idle
 cooling driver

On 8 June 2017 at 14:59, Jean Wangtao <jean.wangtao@...aro.org> wrote:
>
> Hi Vincent,
>
> 2017年6月8日 下午3:19，"Vincent Guittot" <vincent.guittot@...aro.org>写道：
>
> Hi Kevin,
>
> On 5 June 2017 at 11:07, Tao Wang <kevin.wangtao@...ilicon.com> wrote:
>> cpu idle cooling driver performs synchronized idle injection across
>> all cpu in same cluster, offers a new method to cooling down cpu,
>> that is similar to intel_power_clamp driver, but is basically
>> designed for ARM platform.
>> Each cluster has its own idle cooling device, each core has its own
>> idle injection thread, idle injection thread use play_idle to enter
>> idle. In order to reach deepest idle state, all cores are aligned by
>> jiffies. the injected idle ratio can be controlled through cooling
>> device interface.
>>
>> Signed-off-by: Tao Wang <kevin.wangtao@...ilicon.com>
>> ---
>>  drivers/thermal/Kconfig            |   13 +
>>  drivers/thermal/Makefile           |    3 +
>>  drivers/thermal/cpu_idle_cooling.c |  648
>> ++++++++++++++++++++++++++++++++++++
>>  3 files changed, 664 insertions(+)
>>  create mode 100644 drivers/thermal/cpu_idle_cooling.c
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index b5b5fac..f78e85c 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -154,6 +154,19 @@ config CPU_THERMAL
>>
>>           If you want this support, you should say Y here.
>>
>> +config CPU_IDLE_THERMAL
>> +       tristate "generic cpu idle cooling support"
>> +       depends on CPU_FREQ
>
> Does CPU_IDLE_THERMAL really depend on CPU_FREQ ?
>
>
> because I use a interface of cpufreq to get cpu idle time and current wall
> time, that cause the dependency

IMO, you should better use directly get_cpu_idle_time_us and remove
your dependency with cpufreq
Furthermore, get_cpu_idle_time from cpufreq may consider iowait as
busy time which could make sense for cpufreq but not really for idle
injection


>
> This dependency should be put for CPU_THERMAL_COMBO in the patch 2
>
>
> CPU_THERMAL_COMBO depend on CPU_THERMAL and CPU_IDLE_THERMAL, but the code
> of patch 2 have no direct relationship with cpufreq, so I didn't add the
> dependency

yes you're right, CPU_THERMAL_COMBO depends already on CPUFREQ

>
>
>> +       help
>> +         This implements the generic cpu cooling mechanism through idle
>> +         injection.
>> +
>> +         This will throttle cpu by injecting specified idle time in
>> +         a fixed cycle. All cpu in same cluster will enter idle
>> synchronously
>> +         to reach deepest idle state when injecting idle.
>> +
>> +         If you want this support, you should say Y here.
>> +
>>  config CLOCK_THERMAL
>>         bool "Generic clock cooling support"
>>         depends on COMMON_CLK
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 094d703..a4db66e 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -26,6 +26,9 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL)   += clock_cooling.o
>>  # devfreq cooling
>>  thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
>>
>> +# cpu idle cooling
>> +obj-$(CONFIG_CPU_IDLE_THERMAL) += cpu_idle_cooling.o
>> +
>>  # platform thermal drivers
>>  obj-y                          += broadcom/
>>  obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)     += qcom-spmi-temp-alarm.o
>> diff --git a/drivers/thermal/cpu_idle_cooling.c
>> b/drivers/thermal/cpu_idle_cooling.c
>> new file mode 100644
>> index 0000000..89a15c5
>> --- /dev/null
>
> [snip]
>
>