Re: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes

[John Stultz]

On Wed, Jul 13, 2016 at 4:02 PM, Paul E. McKenney
<paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Jul 13, 2016 at 03:39:37PM -0700, John Stultz wrote:
>>
>> But otherwise both patches look great and are working well!
>>
>> Do you mind marking them both for stable 4.4+?
>
> OK, looks like it does qualify in the "fix a notable performance or
> interactivity issue" category.
>
>> Tested-by: John Stultz <john.stultz@xxxxxxxxxx>
>> Acked-by: John Stultz <john.stultz@xxxxxxxxxx>
>>
>> Also, do make sure Dmitry gets the reported-by credit for the first patch.
>
> Done!  The updated first patch is below, and the second will follow.

So just as a heads up, while this patch *greatly* improved the
situation, apparently the occasional 7ms spikes (again, much better
then 80ms!) still seen are causing trouble when compared w/ the 4.1 or
earlier kernels (which I think kept things sub-ms - Dmitry, please
correct me).

So I wanted to dampen my enthusiasm a touch for this, as there may yet
further improvements needed.  I'll try to get some more info on this
as soon as I have details.

thanks
-john