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Bug 1830738 - Sanlock fails to setup real time priority when running as service
Summary: Sanlock fails to setup real time priority when running as service
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: sanlock
Version: 8.2
Hardware: Unspecified
OS: Unspecified
unspecified
high
Target Milestone: rc
: 8.0
Assignee: David Teigland
QA Contact: cluster-qe@redhat.com
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2020-05-03 15:09 UTC by Nir Soffer
Modified: 2021-09-07 12:04 UTC (History)
3 users (show)

Fixed In Version: sanlock-3.8.2-1.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2020-11-04 02:14:39 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2020:4595 0 None None None 2020-11-04 02:14:49 UTC

Description Nir Soffer 2020-05-03 15:09:31 UTC 
Description of problem:

During startup sanlock tries to use real time priority, but this always fails:
    
2020-04-30 14:40:49 7 [903]: sanlock daemon started 3.8.0 host 68375b9c-ef41-4214-ab83-a170c2e07ca3.host4
2020-04-30 14:40:49 7 [903]: set scheduler RR|RESET_ON_FORK priority 99 failed: Operation not permitted

So sanlock runs with normal priority. This may cause delays and failures
to renew leases.

Version-Release number of selected component (if applicable):
Tested with 3.8.0, but looking at git history this seems to 
a very old issue.

How reproducible:
Always

Steps to Reproduce:
1. Start the service

Actual results:
# ps -o cmd,cls,rtprio -p 903
CMD                         CLS RTPRIO
/usr/sbin/sanlock daemon     TS      -

Expected results:
$ ps -o cmd,cls,rtprio -p 2275
CMD                         CLS RTPRIO
/usr/sbin/sanlock daemon     RR     99

This may be related to I/O timeouts we experience in oVirt system tests.
See bug 1247135

Fix posted upstream:
https://lists.fedorahosted.org/archives/list/sanlock-devel@lists.fedorahosted.org/message/J64ENSHB6Q3AST4H3PDJARDNYLSTLWAF/
Comment 1 Nir Soffer 2020-05-08 17:49:32 UTC 
This is probably not related to timeouts in oVirt system tests mention
in bug 1247135. We found that the issue is bug 1832967.
Comment 2 David Teigland 2020-08-12 19:13:34 UTC 
Setting the scheduler has simply been removed, so this is no longer a problem.

It looks like the research we did on this issue several months ago never made it into bz, or there was some other bz it went into that I can't find.  The conclusion was that setting the scheduler has not worked for many years, and since we didn't notice any problems without it, the setting was unnecessary.  

Based on Nir's research, and talking with scheduler developers, we found that it's not really feasible to enable this even if we wanted to.
Comment 6 Corey Marthaler 2020-08-13 23:25:35 UTC 
Fix verified in the rpms.

# old rpms
sanlock-3.8.1-1.el8    BUILT: Thu Jul  9 14:02:05 CDT 2020
sanlock-lib-3.8.1-1.el8    BUILT: Thu Jul  9 14:02:05 CDT 2020

Aug 13 13:38:52 host-073.virt.lab.msp.redhat.com systemd[1]: Starting Shared Storage Lease Manager...
Aug 13 13:38:53 host-073.virt.lab.msp.redhat.com systemd[1]: Started Shared Storage Lease Manager.
Aug 13 13:38:53 host-073.virt.lab.msp.redhat.com sanlock[4106]: 2020-08-13 13:38:53 405 [4106]: set scheduler RR|RESET_ON_FORK priority 99 failed: Operation not permitted


# new rpms
sanlock-3.8.2-1.el8    BUILT: Mon Aug 10 12:12:49 CDT 2020
sanlock-lib-3.8.2-1.el8    BUILT: Mon Aug 10 12:12:49 CDT 2020

[root@host-083 ~]# systemctl status sanlock
â— sanlock.service - Shared Storage Lease Manager
   Loaded: loaded (/usr/lib/systemd/system/sanlock.service; disabled; vendor preset: disabled)
   Active: active (running) since Thu 2020-08-13 18:20:44 CDT; 1min 48s ago
  Process: 3337 ExecStart=/usr/sbin/sanlock daemon (code=exited, status=0/SUCCESS)
 Main PID: 3341 (sanlock)
    Tasks: 6 (limit: 93971)
   Memory: 14.7M
   CGroup: /system.slice/sanlock.service
           ├─3341 /usr/sbin/sanlock daemon
           └─3342 /usr/sbin/sanlock daemon

Aug 13 18:20:44 host-083.virt.lab.msp.redhat.com systemd[1]: Starting Shared Storage Lease Manager...
Aug 13 18:20:44 host-083.virt.lab.msp.redhat.com systemd[1]: Started Shared Storage Lease Manager.
Comment 9 errata-xmlrpc 2020-11-04 02:14:39 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 (sanlock 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/RHBA-2020:4595
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