Hello, Waiman.

On Mon, Aug 27, 2018 at 10:41:24AM -0400, Waiman Long wrote:

Cpuset allows arbitrary modification of cpu list in "cpuset.cpus"
even if the requested CPUs won't be granted in "cpuset.cpus.effective"
as restricted by its parent. However, the validate_change() function
will inhibit removal of CPUs that have been used in child cpusets.

Being a partition root, however, limits the kind of cpu list
modification that is allowed. Adding CPUs is not allowed if the new
CPUs are not in the parent's effective cpu list that can be put into
"cpuset.cpus.reserved". In addition, a child partition cannot exhaust
all the parent's effective CPUs.

Because of the implicit cpu exclusive nature of the partition root,
cpu changes that break that cpu exclusivity will not be allowed. Other
changes that break the conditions of being a partition root is generally
allowed. However, the partition flag of the cpuset as well those of
the descendant partitions will be forcefully turned off.

First of all, thanks a lot for your persistence.  I'm not necessarily
against the flag being forced off but wonder whether the same
config/effective approach can be used as in .cpus and .mems.  Can you
elaborate a bit on the choice here?

Thank you.

-- 
tejun