Re: [PATCH] sched/cpufreq: don't trigger cpufreq update w/o real rt/deadline tasks running

[Wanpeng Li]

2016-04-20 22:01 GMT+08:00 Peter Zijlstra <peterz@xxxxxxxxxxxxx>:
> On Wed, Apr 20, 2016 at 02:32:35AM +0200, Rafael J. Wysocki wrote:
>> On Monday, April 18, 2016 01:51:24 PM Wanpeng Li wrote:
>> > Sometimes update_curr() is called w/o tasks actually running, it is
>> > captured by:
>> >     u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;
>> > We should not trigger cpufreq update in this case for rt/deadline
>> > classes, and this patch fix it.
>> >
>> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>>
>> The signed-off-by tag should agree with the From: header.  One way to achieve
>> that is to add an extra From: line at the start of the changelog.
>>
>> That said, this looks like a good catch that should go into 4.6 to me.
>>
>> Peter, what do you think?
>
> I'm confused by the Changelog. *what* ?

Sometimes .update_curr hook is called w/o tasks actually running, it is
captured by:

        u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start;

We should not trigger cpufreq update in this case for rt/deadline
classes, and this patch fix it.

Regards,
Wanpeng Li