Bug 1041263 - [RFE][nova]: Explicit use of hugepages with libvirt
Summary: [RFE][nova]: Explicit use of hugepages with libvirt
Keywords:
Status: CLOSED UPSTREAM
Alias: None
Product: Red Hat OpenStack
Classification: Red Hat
Component: RFEs
Version: unspecified
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
: ---
Assignee: RHOS Maint
QA Contact:
URL: https://blueprints.launchpad.net/nova...
Whiteboard: upstream_milestone_none upstream_stat...
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-12-12 14:12 UTC by RHOS Integration
Modified: 2015-03-19 17:35 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of:
Environment:
Last Closed: 2015-03-19 17:35:20 UTC
Target Upstream Version:

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Description RHOS Integration 2013-12-12 14:12:05 UTC 
Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/explicit-libvirt-hugepages.

Description:

Transparent hugepages are nice and easy to get working, but do not survive memory pressure on the host. I/O pressure on the host breaks the 2M pages back to 4k pages, and therefore renders transparent hugepages useless for long-lived processes, as nothing will reassemble the 4k pages back to 2M pages after memory pressure has ceased. Basically, Transparent hugepages are not valid for production environments where memory pressure is normal.

To use hugepages we need to set up 'memorybacking' to 'hugepages' in libvirt.xml. We need also to create a new option flag ('libvirt_hugepages' for example) to toogle the hugepages on and off. 

Extra configuration at OS level is needed (AppArmor for example in debian-ite distros).




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