Bug 1339126
| Summary: | mom.log shows "undefined symbol ksmMergeAcrossNodes" continuously if connected to RHEV-M 3.6 | ||||||
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| Product: | Red Hat Enterprise Virtualization Manager | Reporter: | Martin Tessun <mtessun> | ||||
| Component: | ovirt-engine | Assignee: | Martin Sivák <msivak> | ||||
| Status: | CLOSED ERRATA | QA Contact: | sefi litmanovich <slitmano> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 3.6.0 | CC: | bgraveno, dfediuck, gklein, kshukla, lsurette, mavital, mgoldboi, mtessun, rbalakri, rgolan, Rhev-m-bugs, srevivo, ykaul | ||||
| Target Milestone: | ovirt-3.6.8 | Keywords: | ZStream | ||||
| Target Release: | --- | ||||||
| Hardware: | x86_64 | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: |
The Manager no longer sends Kernel Same-Page Merging (KSM) across nodes to Red Hat Enterprise Virtualization 3.5 hosts.
The Memory Overcommit Manager (MoM) was enhanced to support KSM across nodes in Red Hat Enterprise Virtualization 3.6. However, Red Hat Enterprise Virtualization 3.5 does not have the necessary defaults for it, which means a Red Hat Enterprise Virtualization 3.5 host's MoM policy evaluation fails when the version 3.6 Manager is configured to use the host in 3.5 compatibility mode.
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Story Points: | --- | ||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2016-07-27 14:11:53 UTC | Type: | Bug | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | SLA | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Attachments: |
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Description
Martin Tessun
2016-05-24 08:29:25 UTC
Can you please attach the /etc/vdsm/mom.d/00-defines.policy and 03-ksm.policy files? Also changing mom's log level to DEBUG might be a good idea. Created attachment 1161420 [details]
00-defines and 03-ksm policy from the affected RHEV 3.5 host.
Hi Martin,
I attached the two files.
Changing the verbosity to DEBUG did not show much difference:
2016-05-25 15:09:04,762 - mom.Policy - DEBUG - Results: [0, 1, 1, 0, 1, 0.20000000000000001, 0.050000000000000003, 0.20000000000000001, 0.050000000000000003, 0.0025000000000000001, 'change_big_enough', 'shrink_guest', 'grow_guest', 0.93353991682296333, 'balloon_logic', [], 'guest_qos', [], 300, -50, 64, 1250, 10, 0.20000000000000001, 'change_npages', 784832.0, 0, None, -1, 100000, 'check_and_set_quota', 'reset_quota_and_period', []]
2016-05-25 15:09:06,912 - mom.RPCServer - INFO - setNamedPolicy()
2016-05-25 15:09:06,983 - mom.Policy - INFO - Loaded policy '01-parameters'
2016-05-25 15:09:09,054 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:14,060 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:14,779 - mom.Policy - ERROR - Policy error: undefined symbol ksmMergeAcrossNodes
2016-05-25 15:09:19,066 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:24,072 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:24,793 - mom.Policy - ERROR - Policy error: undefined symbol ksmMergeAcrossNodes
2016-05-25 15:09:29,078 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:34,084 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:34,812 - mom.Policy - ERROR - Policy error: undefined symbol ksmMergeAcrossNodes
2016-05-25 15:09:39,091 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:44,097 - mom.vdsmInterface - DEBUG - VM List: []
2016-05-25 15:09:44,833 - mom.Policy - ERROR - Policy error: undefined symbol ksmMergeAcrossNodes
Cheers,
Martin
Ah, I know what the issue is now. I thought it is a bad upgrade, but it actually is quite the opposite. The engine is sending a value for a variable that is not present in the RHEL 6 MOM version. We can either fix that on the engine side or on the MOM side.. I wonder what is better: - engine not sending the value when on 3.5 cluster compatibility level - adding a support for that value to mom although it will be ignored This has a simple workaround fortunately. Just add the following to 00-defines.policy (defvar ksmMergeAcrossNodes 0) (defvar ioTuneEnabled 0) The other one is also related to 3.6 feature and might cause the same issue if somebody enables it. just small fix to prevent 3.5 cluster from sending the ksm attributes Changing the component as this has to happen on the engine side. *** Bug 1343109 has been marked as a duplicate of this bug. *** Verified with ENGINE: rhevm-3.6.8-0.1.el6.noarch HOST: RHEL 6.7 vdsm (3.5) - vdsm-4.16.38-1.el6ev.x86_64 mom - mom-0.4.1-4.el6ev.noarch Verified according to steps in description, the error message wasn't issued at any point in mom.log. 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, 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://rhn.redhat.com/errata/RHBA-2016-1507.html |