Bug 1552696

Summary: realtime-virtual-host,guest: enable timer migration
Product: Red Hat Enterprise Linux 7 Reporter: Luiz Capitulino <lcapitulino>
Component: tunedAssignee: Jaroslav Škarvada <jskarvad>
Status: CLOSED WONTFIX QA Contact: qe-baseos-daemons
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 7.5CC: jeder, jskarvad, mtosatti, olysonek
Target Milestone: rc   
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Hardware: Unspecified   
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: 1779719 (view as bug list) Environment:
Last Closed: 2020-01-10 14:38:44 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Blocks: 1240765, 1709724, 1779719    
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Description Flags
add kernel.timer_migration 1 to KVM-RT profiles none

Description Luiz Capitulino 2018-03-07 14:50:59 UTC 
Description of problem:

The realtime-virtual-host profile doesn't have sysctl kernel.migration set, as a result if the thread running on a RT CPU starts a (non-irq-context) timer, the timer will probably interrupt the running thread as opposed to being migrated to a housekeeping CPU.

This is probably not as serious as it seems, since the RT apps expected to run in KVM-RT don't start such timers. But this is impacting tscdeadline_latency when activating the profile, since QEMU starts such a timer for a brief period of time.


Version-Release number of selected component (if applicable): tuned-2.9.0-1.el7.noarch
Comment 2 Luiz Capitulino 2018-03-07 15:09:25 UTC 
Created attachment 1405399 [details]
add kernel.timer_migration 1 to KVM-RT profiles
Comment 3 Jaroslav Škarvada 2020-01-10 14:38:44 UTC 
Red Hat Enterprise Linux version 7 entered the Maintenance Support 1 phase in August 2019. In this phase only qualified Critical and Important Security errata advisories (RHSAs) and Urgent Priority Bug Fix errata advisories (RHBAs) may be released as they become available. Other errata advisories may be delivered as appropriate.

This bug has been reviewed by Support and Engineering representative and does not meet the inclusion criteria for Maintenance Support 1 phase.

For more information about Red Hat Enterprise Linux Lifecycle, please see https://access.redhat.com/support/policy/updates/errata#Maintenance_Support_1_Phase.