Messages in this thread | | | Date | Wed, 5 Jun 2019 16:20:03 +0200 | From | Michal Koutný <> | Subject | Re: [PATCH] sched/core: Fix cpu controller for !RT_GROUP_SCHED |
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On Wed, Jun 05, 2019 at 01:49:35PM +0200, Juri Lelli <juri.lelli@redhat.com> wrote: > Existing code comes with a comment saying the "we don't support RT-tasks > being in separate groups". I'm also inclined to this check not being completely correct.
This guard also prevents enabling cpu controller on unified hierarchy with !CONFIG_RT_GROUP_SCHED. (If there are any kernel RT threads in root cgroup, they can't be migrated to the newly create cpu controller's root in cgroup_update_dfl_csses().)
I considered relaxing the check to non-root cgroups only, however, as your example shows, it doesn't prevent reaching the avoided state by other paths. I'm not that familiar with RT sched to tell whether RT-priority tasks in different task_groups break any assumptions.
Michal
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