On 7/28/21 12:09 PM, Michal Koutný wrote:
Hello Waiman.
On Tue, Jul 20, 2021 at 10:18:31AM -0400, Waiman Long <longman@xxxxxxxxxx> wrote:
@@ -2026,6 +2036,22 @@ static int update_prstate(struct cpuset *cs, int new_prs)
[...]
+ } else if (old_prs && new_prs) {
If an isolated root partition becomes invalid (new_prs == PRS_ERROR)...
+ /*
+ * A change in load balance state only, no change in cpumasks.
+ */
+ update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED));
...this seems to erase information about CS_SCHED_LOAD_BALANCE zeroness.
IOW, if there's an isolated partition that becomes invalid and later
valid again (a cpu is (re)added), it will be a normal root partition
without the requested isolation, which is IMO undesired.
I may have overlooked something in broader context but it seems to me
the invalidity should be saved independently of the root/isolated type.
PRS_ERROR cannot be passed to update_prstate(). For this patchset,
PRS_ERROR can only be set by changes in hotplug. The current design will
maintain the set flag (CS_SCHED_LOAD_BALANCE) and use it to decide to
switch back to PRS_ENABLED or PRS_ISOLATED when the cpus are available
again.
Cheers,
Longman
