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

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Date:	Thu, 20 Jun 2013 20:18:33 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	rjw@...k.pl, 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 06/20/2013 07:59 PM, Chanwoo Choi wrote:
> On 06/20/2013 07:55 PM, Viresh Kumar wrote:
>> On 20 June 2013 16:15, Chanwoo Choi <cw00.choi@...sung.com> wrote:
>>> Yes, freq->old is same freq->new.
>>>
>>> The cpufreq gorvernor(dbs_check_cpu()) send CPUFREQ_LOADCHECK noti
>>> right after calculating CPUs load, regardless of changing CPU frequency.
>>> So, I use only freq->old value without using freq->new because load_table
>>> debugfs file need current cpu frequency.
>>>
>>> Now, I can't think of any proper usage for freq->new.
>>> Do you have good way for using freq->new to include more useful data in load_table?
>>
>> This information might be interesting.. At what load, we moved from
>> which freq to which one..
>>
>> Just see if you can add the notification after frequency has been
>> changed.
>>
> OK, I'll modify it and send test result. Thanks.
> 
> Best Regards,
> Chanwoo Choi
> 

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?

Thanks,
Chanwoo Choi
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