Bug 2219530

Summary:	pods get restarted due to failed probes
Product:	Red Hat Enterprise Linux 8	Reporter:	cshulyup
Component:	kernel-rt	Assignee:	Eder Zulian <ezulian>
kernel-rt sub component:	Scheduler	QA Contact:	Waylon Cude <wcude>
Status:	VERIFIED ---	Docs Contact:
Severity:	high
Priority:	high	CC:	bhu, bwensley, chuhu, ezulian, jlelli, llong, minlei, mstowell, qzhao, yizhan
Version:	8.6	Keywords:	Triaged, ZStream
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	kernel-rt-4.18.0-505.rt7.294.el8	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	2227238 2227239 2227240 (view as bug list)		Environment:
Last Closed:		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:
Bug Depends On:
Bug Blocks:	2227238, 2227239, 2227240

Description cshulyup 2023-07-04 07:22:52 UTC

The issue doesn't happen when CFS throttling (quota) is disabled or on periodic (nohz=off) kernel.

Probes fails because of exhausted quota.
The quota is exhausted due to delayed quota refill.
The refill is delayed because hrtimers are delayed. 
hrtimers are delayed because of missed interrupts.
Interrupts at missed because of nohz mode.

Steps to Reproduce:
1. install SNO
2. install https://gitlab.cee.redhat.com/cshulyup/vdu-workload-emulator/-/tree/base?ref_type=heads by running script ./add_test-deployments.sh
3. monitor pods restarts with command `oc get pods -n test | grep ago` for 10 (ten) days.

Actual results:
- some pods are restarted after several days

Expected results:
- no single pod restart during 10 days (240 hours)

The fix:
- patch "softirq: Wake ktimers thread also in softirq",
already merged to other branches:
- https://gitlab.com/redhat/rhel/src/kernel/rhel-9/-/merge_requests/695
- https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2543/


Additional info:
- https://issues.redhat.com/browse/OCPBUGS-3547
- 
https://docs.google.com/document/d/14aYlleo7EaYAjY6QM45AUQ9bw6FUlL20zIkqoyx4PiY/edit#heading=h.jwttsod63yqc

Comment 5 Ming Lei 2023-07-11 01:46:27 UTC

*** Bug 2128603 has been marked as a duplicate of this bug. ***

Comment 6 Eder Zulian 2023-07-11 09:17:01 UTC

*** Bug 2210126 has been marked as a duplicate of this bug. ***

Comment 19 Ming Lei 2023-08-01 02:44:38 UTC

Hello Guys,

Looks the fix only lands kernel-rt, any chance to make it to rhel8.9(kernel)?

Because we have Bug 2128603 which can be fixed by this change.


Thanks,