Bug 1701394
| Summary: | tuned-profiles-sap: tuned.conf should not set kernel.sem lower than RHEL 8 default | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | Bernd Finger <bfinger> |
| Component: | tuned | Assignee: | Jaroslav Škarvada <jskarvad> |
| Status: | CLOSED ERRATA | QA Contact: | Robin Hack <rhack> |
| Severity: | medium | Docs Contact: | |
| Priority: | high | ||
| Version: | 8.0 | CC: | bfinger, fdanapfe, hannsj_uhl, jeder, jskarvad, olysonek, rhack, tgummels |
| Target Milestone: | rc | Keywords: | Patch, Upstream |
| Target Release: | 8.1 | Flags: | pm-rhel:
mirror+
|
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | tuned-2.12.0-0.1.rc1.el8 | Doc Type: | If docs needed, set a value |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2019-11-05 22:31:10 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: | 1654309, 1710589 | ||
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Description
Bernd Finger
2019-04-18 20:45:22 UTC
In rhel-7, the defaults are the following: $ sysctl kernel.sem kernel.sem = 250 32000 32 128 So it appears the intent of the profile was indeed to raise the values. However I was not able to dig up where the values in the Tuned profile came from, so I'm not able to verify that the rhel-8 defaults are sane. Jardo, could you help with that? Maybe Frank could answer this. Do we need to increase kernel.sem on RHEL-8 for SAP or are the defaults good enough? If there is a need to increase, to which values? (In reply to Jaroslav Škarvada from comment #2) > Maybe Frank could answer this. Do we need to increase kernel.sem on RHEL-8 > for SAP or are the defaults good enough? If there is a need to increase, to > which values? Sorry, I can't help here, since I'm actually not involved in any of the work realtead to SAP software on RHEL8. My colleague Bernd Finger who raised this bugzilla is responsible for the testing et. to get RHEL8 ready for running SAP products, therefore please work with him on this. In general I would say if the defaults for this kernel parameter in RHEL8 are much higher than what the tuned profile is trying to set them to, then it would be better to keep the RHEL 8 defaults and remove the change of this kernel parameter from the tuned profile. RHEL 8 defaults are, as mentioned above: kernel.sem = 32000 1024000000 500 32000 This is much higher than required by SAP, so there is no need to increase them. I had discussed this and similar issues with SAP, and they are fine with using any parameter defaults in case they are higher than current SAP requirements. The reason for setting the kernel.sem values to "1250 256000 100 8192" in RHEL 7 was that the defaults were lower in RHEL 7. As the defaults in RHEL 8 are much higher, there is no need for setting these values in tuned-profiles-sap any more. Does this answer your question? Thanks for info, we will probably add conditional rule to the Tuned profile, i.e. it will increase the value only if it is lower. Would be great if the fix for this issue could be in RHEL 8.1. (In reply to Jaroslav Škarvada from comment #5) > Thanks for info, we will probably add conditional rule to the Tuned profile, > i.e. it will increase the value only if it is lower. Jaroslav, Will you be able to tackle this for 8.1? Travis (In reply to Travis Gummels from comment #7) > (In reply to Jaroslav Škarvada from comment #5) > > Thanks for info, we will probably add conditional rule to the Tuned profile, > > i.e. it will increase the value only if it is lower. > > Jaroslav, > > Will you be able to tackle this for 8.1? > > Travis Yes, we are going to address this in 8.1. (In reply to Jaroslav Škarvada from comment #5) > Thanks for info, we will probably add conditional rule to the Tuned profile, > i.e. it will increase the value only if it is lower. The problem with that is that the '=>' operator (which can be used in Tuned profiles to achieve the conditional rule) does not currently support complex values such as '1250 256000 100 8192'. And it's not clear to me exactly how the operator should behave in this case. There might even be a relationship between the individual values. Changing the values independently could result in sub-optimal settings. I hope that makes sense. So I propose we don't make this unnecessarily complicated and go with the same solution as we agreed in bug#1708418 - change the value in the profile to the RHEL-8 default. Bernd, should we change the value in all the SAP profiles (sap-hana-vmware, sap-hana, sap-netweaver), or just sap-netweaver? Thanks! Upstream pull request: https://github.com/redhat-performance/tuned/pull/190 (In reply to Ondřej Lysoněk from comment #10) > Bernd, should we change the value in all the SAP profiles (sap-hana-vmware, > sap-hana, sap-netweaver), or just sap-netweaver? Thanks! I forgot we're removing sap-hana-vmware. So the question should be: do we need to change the value in the sap-hana profile as well as sap-netweaver? Hi Ondřej, I could not find kernel.sem in the install guide for SAP HANA 2 SPS04 (which is the latest HANA version) nor in any other SAP note related to SAP HANA. However, as kernel.sem is in the current version of sap-hana/tuned.conf, and as we are just setting the RHEL 8 defaults, it should be safe to just put it in both tuned.conf files (for sap-netweaver and sap-hana). Also it is certainly useful for those cases where customers accidentally have lowered kernel.sem. So please set this value in both the SAP profiles (sap-hana and sap-netweaver). QA_ACK+ RHEL8.1 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://access.redhat.com/errata/RHBA-2019:3633 |