linux-kernel - Re: [PATCH v2] cpufreq: stats: Add 'load_table' debugfs file to show accumulated data of CPUs

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Date:	Mon, 24 Jun 2013 17:32:09 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>
Subject: Re: [PATCH v2] cpufreq: stats: Add 'load_table' debugfs file to show
 accumulated data of CPUs

On 06/21/2013 10:13 PM, Rafael J. Wysocki wrote:
> On Friday, June 21, 2013 01:01:35 PM Chanwoo Choi wrote:
>> On 06/21/2013 12:42 AM, Viresh Kumar wrote:
>>> On 20 June 2013 16:48, Chanwoo Choi <cw00.choi@...sung.com> wrote:
>>>> But,
>>>> To show old frequency/new frequency on load_table debugfs file,
>>>> governor function(dbs_check_cpu()) pass calculated CPUs load to specific governor(e.g., ondemand)
>>>> as below function flow.
>>>>
>>>> dbs_check_cpu() (in cpufreq.c)
>>>> -> od_check_cpu() (in cpufreq_ondemand.c)
>>>> -> __cpufreq_driver_target() (in cpufreq.c)
>>>> -> cpufreq_driver->target(policy)
>>>>
>>>> Also, The __cpufreq_driver_target() is external function which can be called on other file
>>>> so I must consider exception case.
>>>>
>>>> If send CPUFREQ_LOADCHECK noti after changed cpu frequency,
>>>> I think it is complicated and has quite a little difficulty.
>>>>
>>>> What is your opinion?
>>>
>>> What you can do is:
>>> - create another routine: cpufreq_governor_driver_target()
>>> - replace all __cpufreq_driver_target() from ondemand/conservative governors
>>> with this one
>>> - In cpufreq_governor_driver_target() call __cpufreq_driver_target() and
>>> take a note of new freq.
>>>
>>> Maybe you don't need to check the actual freq that is set (even
>>> that would be simple to implement), but what is requested.
>>>
>>
>> OK, I understand and will try to implement it.
>> Thanks.
>>
>> @Rafael?
>> If possible, I want to know the your opinion about this.
> 
> Well, to be honest, I don't like the whole thing.  The more changes you need
> to make to the common code to support it, the worse.
> 

To minimize the modification of cpufreq core, I implemented load_table debugfs file
by only using CPUFREQ_LOADCHECK and CPUFREQ_POSTCHANGE noti. So, I don't add additional
function for load_table debugfs file. I will send next version patch for load_table soon.

Best Regards,
Chanwoo Choi

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