On 08/17/2018 11:59 AM, Tejun Heo wrote:

Hello, Waiman.

On Mon, Aug 13, 2018 at 01:56:15PM -0400, Waiman Long wrote:

quoted

The following restrictions are still imposed on a partition root wrt
allowable changes in cpuset.cpus:
1) cpuset.cpus cannot be set to "". There must be at least 1 cpu there.
2) Adding cpus that are not in parent's cpuset.cpus (as well as
cpuset.cpus.effective) or that will take all the parent's effective cpus
away is not allowed.

So are these limitations acceptable?

The easiest way to remove those restrictions is to forcefully turn off
the cpuset.sched.partition flag in the cpuset as well as any
sub-partitions when the user try to do that. With that change, there
will be no more new restriction on what you can do on cpuset.cpus.

I think that'd be the right thing to do.  That's what we do with
cpuset.cpus and cpuset.mems too.  If there's nothing available, we
ignore the config and show the settings which are currently in effect.

Thanks.

Thanks! I will send out an updated patch after the 4.19 merge window closes.

-Longman