Bug 1646397

Summary:	[RFE] Performance Monitoring Unit management for real time guest
Product:	Red Hat OpenStack	Reporter:	jianzzha
Component:	openstack-nova	Assignee:	smooney
Status:	CLOSED ERRATA	QA Contact:	Paras Babbar <pbabbar>
Severity:	high	Docs Contact:
Priority:	medium
Version:	13.0 (Queens)	CC:	acanan, amodi, ccopello, cfontain, dasmith, egallen, eglynn, fbaudin, fiezzi, jhakimra, jianzzha, kchamart, lcapitulino, lyarwood, mbooth, mtosatti, nlevinki, nwolf, sbauza, scohen, sgordon, smooney, stephenfin, vromanso
Target Milestone:	Upstream M3	Keywords:	FutureFeature, Patch, Triaged
Target Release:	16.0 (Train on RHEL 8.1)
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	openstack-nova-20.0.1-0.20191025043858.390db63.el8ost	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-02-06 14:39:53 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:	1640832, 1769450

Description jianzzha 2018-11-05 14:10:38 UTC

Description of problem:
Real time guest requires <features>pmu state='off'.

For backward compatibility, it might be better to add an explicit hw:pmu_state=on|off extraspec/image metadata key.


Version-Release number of selected component (if applicable):
OSP13

Comment 1 Luiz Capitulino 2018-11-05 14:19:28 UTC

The PMU emulation in KVM increases wakeup latency by some microseconds when running cyclictest, so we need to be able to turn it off.

Comment 4 smooney 2018-11-09 16:29:37 UTC

this is a valid request but it will require a spec upstream and to write it we will need to have a performance assessment of  the impact of enabling or not enabling it on realtime workloads. can you link to any public assessment that can be used to justify this upstream.

this may be back portable as it should not involve any api change but we will not know that until the feature is implemented. we are significantly past the window for new features for OSP 15 so i am provisionally targeting this for OSP 16.

Comment 15 smooney 2019-08-21 11:21:15 UTC

This has now merged on master so setting to post.

Comment 18 Artom Lifshitz 2019-11-25 18:24:13 UTC

Some whitebox tests have merged for this: https://review.opendev.org/#/c/695551/

Comment 25 errata-xmlrpc 2020-02-06 14:39:53 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, 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/RHEA-2020:0283