Re: CFS Bandwidth Control - Test results of cgroups tasks pinned vsunpinnede

From: Srivatsa Vaddagiri
Date: Tue Sep 13 2011 - 01:03:31 EST


* Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx> [2011-09-13 09:45:45]:

> * Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> [2011-09-12 14:35:43]:
>
> > Of course it does.. and I bet you can improve that slightly if you
> > manage to fix some of the numerical nightmares that live in the cgroup
> > load-balancer (Paul, care to share your WIP?)
>
> Booting with "nohz=off" also helps significantly.
>
> With nohz=on, average idle time (over 1 min) is 10.3%
> With nohz=off, average idle time (over 1 min) is 3.9%

Tuning min_interval and max_interval of various sched_domains to 1 [a]
and also setting sched_cfs_bandwidth_slice_us to 500 does cut down idle
time further to 2.7% ..

This is perhaps not optimal (as it may lead to more lock contentions), but
something to note for those who care for both capping and utilization in
equal measure!

- vatsa

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