On Thu, May 24, 2018 at 02:53:31PM -0400, Waiman Long wrote:

On 05/24/2018 11:41 AM, Peter Zijlstra wrote:

quoted

On Thu, May 17, 2018 at 04:55:41PM -0400, Waiman Long wrote:

quoted

A new cpuset.sched.domain boolean flag is added to cpuset v2. This new
flag indicates that the CPUs in the current cpuset should be treated
as a separate scheduling domain.

The traditional name for this is a partition.

Do you want to call it cpuset.sched.partition? That name sounds strange
to me.

Let me explore the whole domain x load-balance space first. I'm thinking
the two parameters are mostly redundant, but I might be overlooking
something (trivial or otherwise).

quoted

quoted

+  cpuset.sched.domain
+	A read-write single value file which exists on non-root
+	cpuset-enabled cgroups.  It is a binary value flag that accepts
+	either "0" (off) or a non-zero value (on).

I would be conservative and only allow 0/1.

I stated that because echoing other integer value like 2 into the flag
file won't return any error. I will modify it to say just 0 and 1.

Ah, I would make the file error on >1.

Because then you can always extend the meaning afterwards because you
know it won't be written to with the new value.

quoted

quoted

+	3) There is no child cgroups with cpuset enabled.
+
+	Setting this flag will take the CPUs away from the effective
+	CPUs of the parent cgroup. Once it is set, this flag cannot be
+	cleared if there are any child cgroups with cpuset enabled.

This I'm not clear on. Why?

That is for pragmatic reason as it is easier to code this way. We could
remove this restriction but that will make the code more complex.

Best to mention that I think.
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