Re: [PATCH v3 0/9] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus
From: Waiman Long
Date: Tue Jul 27 2021 - 17:14:36 EST
On 7/26/21 7:17 PM, Tejun Heo wrote:
Hello,
On Tue, Jul 20, 2021 at 10:18:25AM -0400, Waiman Long wrote:
v3:
- Add two new patches (patches 2 & 3) to fix bugs found during the
testing process.
- Add a new patch to enable inotify event notification when partition
become invalid.
- Add a test to test event notification when partition become invalid.
I applied parts of the series. I think there was a bit of miscommunication.
I meant that we should use the invalid state as the only way to indicate
errors as long as the error state is something which can be reached through
hot unplug or other uncontrollable changes, and require users to monitor the
state transitions for confirmation and error handling.
Yes, that is the point of adding the event notification patch.
In the current code, direct write to cpuset.cpus.partition are strictly
controlled and invalid transitions are rejected. However, changes to
cpuset.cpus that do not break the cpu exclusivity rule or cpu hot plug
may cause a partition to changed to invalid. What is currently done in
this patchset is to add extra guards to reject those cpuset.cpus change
that cause the partition to become invalid since changes that break cpu
exclusivity rule will be rejected anyway. I can leave out those extra
guards and allow those invalid cpuset.cpus change to go forward and
change the partition to invalid instead if this is what you want.
However, if we have a complicated partition setup with multiple child
partitions. Invalid cpuset.cpus change in a parent partition will cause
all the child partitions to become invalid too. That is the scenario
that I don't want to happen inadvertently. Alternatively, we can
restrict those invalid changes if a child partition exist and let it
pass through and make it invalid if it is a standalone partition.
Please let me know which approach do you want me to take.
Cheers,
Longman