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SubjectRe: [PATCH v1 00/10] Optimize sched avgs computation and implement flat util hierarchy
On Wed, Aug 10, 2016 at 08:14:45AM +0800, Yuyang Du wrote:
> Hi Peter,
>
> I should have sent out my flat util hierarchy implementation long time ago,
> actually code was there but not rebased. I finally have time to do this,
> so here it is. There are also other proposals to solve migrated tasks' util
> mobility problem, such as the ones from Dietmar and Vincent.
>
> The sched avgs computation optimization was initiated for the flat util thing,
> so I send them out together.
>
> According to Morten and Ben's feedback, I removed 32-bit as a period's upper
> bound limit. So, thanks a lot to them.
>

To compare the effectiveness of the flat util hierarchy, a simple experiment
was done: rt-app to generate a 50% duty-cycling workload (100us/200us), and
in the meantime a script to set the CPU affinity of the task, alternating
to taskset the task to run on CPU x and CPU y every 0.3 sec, so forcing the
task to ping-pong migrate. By auto-group and ssh itself, the task under test
is at the third level task group.

So compare the top cfs_rq's util_avg (group_hierarchy.jpg) vs. the rq's util_avg
(flat_hierarchy.jpg)

Thanks,
Yuyang
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