Re: [PATCH v3 4/9] cgroup/cpuset: Enable event notification when partition become invalid

From: Waiman Long
Date: Tue Jul 27 2021 - 16:26:40 EST

On 7/26/21 7:14 PM, Tejun Heo wrote:
On Tue, Jul 20, 2021 at 10:18:29AM -0400, Waiman Long wrote:
+static inline void notify_partition_change(struct cpuset *cs,
+ int old_prs, int new_prs)
+ if ((old_prs == new_prs) ||
+ ((old_prs != PRS_ERROR) && (new_prs != PRS_ERROR)))
+ return;
+ cgroup_file_notify(&cs->partition_file);
I'd generate an event on any state changes. The user have to read the file
to find out what happened anyway.


From my own testing with "inotify_add_watch(fd, file, IN_MODIFY)", poll() will return with a event whenever a user write to cpuset.cpus.partition control file. I haven't really look into the sysfs code yet, but I believe event generation will be automatic in this case. So I don't think I need to explicitly add a cgroup_file_notify() when users modify the control file directly. Other indirect modification may cause the partition value to change to/from PRS_ERROR and I should have captured all those changes in this patchset. I will update the patch to note this point to make it more clear.