Bug 1980362
| Summary: | Disable CONFIG_RT_GROUP_SCHED from default kernel config or allow configuration of RT budget for cgroup v2 | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 9 | Reporter: | Jan Friesse <jfriesse> |
| Component: | kernel | Assignee: | Phil Auld <pauld> |
| kernel sub component: | Control Groups | QA Contact: | Chao Ye <cye> |
| Status: | CLOSED DUPLICATE | Docs Contact: | |
| Severity: | unspecified | ||
| Priority: | unspecified | CC: | arozansk, bhu, cfeist, cye, jlelli, kcarcia, kwenning, llong, longman, pauld |
| Version: | 9.0 | ||
| Target Milestone: | beta | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2021-08-09 17:16:06 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description
Jan Friesse
2021-07-08 13:23:54 UTC
(In reply to Jan Friesse from comment #0) > Description of problem: > RHEL kernel has CONFIG_RT_GROUP_SCHED option enabled making impossible for > userspace application to gain RT priority (by calling sched_setscheduler (0, > SCHED_RR, ... ) until process is moved to root cgroup. Sadly this is causing > problem described in bug 1962768. Yes, this is a known issue and we are considering disabling CONFIG_RT_GROUP_SCHED for RHEL9, i.e. option 1. -Longman Fwiw, I've put in an MR against ark to disable this. https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1177 It could use more acks :) (In reply to Phil Auld from comment #3) > Fwiw, I've put in an MR against ark to disable this. > > https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1177 > > It could use more acks :) I am aware you have an outstanding kernel-ark MR. I have just ack'ed it. -Longman (In reply to Waiman Long from comment #4) > (In reply to Phil Auld from comment #3) > > Fwiw, I've put in an MR against ark to disable this. > > > > https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1177 > > > > It could use more acks :) > > I am aware you have an outstanding kernel-ark MR. I have just ack'ed it. Maybe you can update the MR description to add this BZ. -Longman ARK changes don't usually get RHEL BZs associated with them do they? I can certainly add it to the MR comment though if you want. (In reply to Phil Auld from comment #6) > ARK changes don't usually get RHEL BZs associated with them do they? I can > certainly add it to the MR comment though if you want. I am OK if you don't want to add it. It is up to you. Done. I found some other ark patch emails that referenced bugzilla.redhat.com bugs so it seems okay to me. Being in charge of a userspace-daemon (SBD = Storage Based Death) that needs RT-scheduling I ran into similar issues with CONFIG_RT_GROUP_SCHED - already some time back when I tried to extrapolate how RHEL9 kernel might look like from f31 kernel. Adding my comment here as I had tried to identify the situation where extra actions had to be taken because of CONFIG_RT_GROUP_SCHED being set. And the only way I found was checking for "rt_rq[...]:/" in /proc/sched_debug (given it is a kernel with /proc/config disabled). Grepping in debug-statistics is of course surper-ugly. Reference to my code playing with the issue: https://github.com/wenningerk/sbd/commit/763e3a0c2ca87c76dddf598ba3355811300ffa59 Finally it turned of course out that there were no real options to properly deal with the issue (as mentioned above already). But still proper detection and reporting of a doomed kernel-config would be desirable (even if it might not trigger in final RHEL9 once CONFIG_RT_GROUP_SCHED is disabled). *** This bug has been marked as a duplicate of bug 1971867 *** |