Re: [RFC PATCH 3/3] sched: introduce tunables to control soft affinity

From: Srikar Dronamraju
Date: Thu Jul 18 2019 - 06:08:58 EST

* subhra mazumdar <subhra.mazumdar@xxxxxxxxxx> [2019-06-26 15:47:18]:

> For different workloads the optimal "softness" of soft affinity can be
> different. Introduce tunables sched_allowed and sched_preferred that can
> be tuned via /proc. This allows to chose at what utilization difference
> the scheduler will chose cpus_allowed over cpus_preferred in the first
> level of search. Depending on the extent of data sharing, cache coherency
> overhead of the system etc. the optimal point may vary.
> Signed-off-by: subhra mazumdar <subhra.mazumdar@xxxxxxxxxx>
> ---

Correct me but this patchset only seems to be concentrated on the wakeup
path, I don't see any changes in the regular load balancer or the
numa-balancer. If system is loaded or tasks are CPU intensive, then wouldn't
these tasks be moved to cpus_allowed instead of cpus_preferred and hence
breaking this soft affinity.

Thanks and Regards
Srikar Dronamraju