Bug 465532
| Summary: | RFE: libvirt should support KVM huge page backed memory | |||
|---|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | James Ralston <ralston> | |
| Component: | libvirt | Assignee: | Daniel Berrangé <berrange> | |
| Status: | CLOSED RAWHIDE | QA Contact: | Fedora Extras Quality Assurance <extras-qa> | |
| Severity: | medium | Docs Contact: | ||
| Priority: | high | |||
| Version: | rawhide | CC: | berrange, crobinso, hbrock, john.cooper, markmc, nelhawar, veillard, virt-maint | |
| Target Milestone: | --- | |||
| Target Release: | --- | |||
| Hardware: | All | |||
| OS: | Linux | |||
| Whiteboard: | ||||
| Fixed In Version: | Doc Type: | Bug Fix | ||
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 515285 (view as bug list) | Environment: | ||
| Last Closed: | 2009-09-15 10:43:27 UTC | Type: | --- | |
| 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: | 498969 | |||
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Description
James Ralston
2008-10-03 18:40:53 UTC
I definitely do not want to expose the -mem-path implementation detail to users or virt-manager. They simply do not have the knowledge neccessary to understand what this means, nor how to leverage it. If we're to make use of this capability we need to figure out a better way to handle it in libvirt and/or kvm, preferably such that it 'just works' as it does in Xen world without any admin config. Changing to libvirt, because this definitely isn't the job of virt-manager Well, the thing about hugepages is, you pretty much have to allocate them at system startup. But memory reserved for hugepages can't be used normally by regular processes. Also, it's not clear that virtualization could be the exclusive user of hugepages; there might be other things that could want to use hugepages. Honestly, I think to *really* do this right, there needs to be some sort of system startup hook to allocate hugepages and mount hugetlsfs in a standard location (e.g., /hugepages). There also needs to be some sort of configuration program (e.g., system-config-memory) to set the amount of memory allocated as hugepages. (Maybe that could be folder into an existing utility.) Then, when starting a virtual guest, libvirt could inspect /proc/meminfo to see if enough non-reserved hugepages are available to satisfy the virtual guest's memory size. If yes, then libvirt automatically includes –mem-path on the command line; if not, then it doesn't. Optionally, libvirt could expose tunables to virt-manager, so that users could, say, fine-tune which virtual guests grab hugepages, limit the number of hugepages that libvirt will attempt to grab (e.g., if other processes in the system were also wanting to use hugepages), et. al. Thoughts? This bug appears to have been reported against 'rawhide' during the Fedora 10 development cycle. Changing version to '10'. More information and reason for this action is here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping Moving to rawhide since this is an RFE. See also: https://fedoraproject.org/wiki/Features/KVM_Huge_Page_Backed_Memory We're still planning on this for Fedora 12 See bug #515741 for a related kernel issue Latest upstream patches http://www.redhat.com/archives/libvir-list/2009-August/msg00480.html Merged upstream and in rawhide http://libvirt.org/git/?p=libvirt.git;a=commit;h=d823a05aef2baa0927e792322f1af45e18c325bd |