Bug 2219530

Summary: pods get restarted due to failed probes
Product: Red Hat Enterprise Linux 8 Reporter: cshulyup
Component: kernel-rtAssignee: Eder Zulian <ezulian>
kernel-rt sub component: Scheduler QA Contact: Waylon Cude <wcude>
Status: CLOSED ERRATA Docs Contact:
Severity: high    
Priority: high CC: bhu, bwensley, chuhu, ezulian, jlelli, llong, minlei, mstowell, qzhao, yizhan
Version: 8.6Keywords: 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:
: 2227238 2227239 2227240 (view as bug list) Environment:
Last Closed: 2023-11-14 15:24:08 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:
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,
Comment 27 errata-xmlrpc 2023-11-14 15:24:08 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Important: kernel-rt security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2023:6901