On 1/12/26 10:15 AM, Waiman Long wrote:
On 1/12/26 10:08 AM, Michal Koutný wrote:
On Mon, Jan 12, 2026 at 09:51:28AM -0500, Waiman Long
<[email protected]> wrote:
Sorry, I might have missed this comment of yours. The
"cpuset.cpus.exclusive" file lists all the CPUs that can be granted
to its
children as exclusive CPUs. The cgroup root is an implicit partition
root
where all its CPUs can be granted to its children whether they are
online or
offline. "cpuset.cpus.effective" OTOH ignores the offline CPUs as
well as
exclusive CPUs that have been passed down to existing descendant
partition
roots so it may differ from the implicit "cpuset.cpus.exclusive".
Howewer, there's no "cpuset.cpus" configurable nor visible on the root
cgroup. So possibly drop this hunk altogether for simplicity?
Ah, you are right. I thought there was a read-only copy in cgroup
root. Will correct that.
Below is the doc diff between v4 and v5:
diff --git a/Documentation/admin-guide/cgroup-v2.rst
b/Documentation/admin-guide/cgroup-v2.rst
index a3446db96cea..28613c0e1c90 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2641,9 +2641,10 @@ Cpuset Interface Files
The root cgroup is always a partition root and its state cannot
be changed. All other non-root cgroups start out as "member".
- Even though the "cpuset.cpus.exclusive*" control files are not
- present in the root cgroup, they are implicitly the same as
- "cpuset.cpus".
+ Even though the "cpuset.cpus.exclusive*" and "cpuset.cpus"
+ control files are not present in the root cgroup, they are
+ implicitly the same as the "/sys/devices/system/cpu/possible"
+ sysfs file.
When set to "root", the current cgroup is the root of a new
partition or scheduling domain. The set of exclusive CPUs is
Cheers,
Longman
