[libvirt-users] HugePages - can't start guest that requires them

[Martin Kletzander]

On Fri, Jan 30, 2015 at 03:33:43PM -0800, G. Richard Bellamy wrote:
>Hello All,
>
>I'm trying to enable hugepages, I've turned off THP (Transparent Huge
>Pages), and enabled hugepages in memoryBacking, and set my 2MB
>hugepages count via sysctl.
>
>I'm getting "libvirtd[5788]: Failed to autostart VM 'atlas': internal
>error: Unable to find any usable hugetlbfs mount for 16777216 KiB"
>where atlas is one of my guests and 16777216 KiB is the amount of
>memory I'm trying to give to the guest.
>

Looking at the XML:

  <memoryBacking>
    <hugepages>
      <page size='16777216' unit='KiB' nodeset='0'/>

This means you want the guest's memory to be allocated from 16GiB
hugepages.  You probably wanted to put this there:

  <page size='2' unit='MiB' ...

>Yes, i can see the hugepages via numastat -m and hugetlbfs is mounted
>via /dev/hugepages and there is a dir structure
>/dev/hugepages/libvirt/qemu (it's empty).
>
>HugePages is big enough to accommodate the 16G i'm allocating... and
>changing the perms on that directory structure to 777 doesn't work
>either.
>
>Any help is much appreciated.
>
>HOST: http://sprunge.us/SEdc
>GUEST: http://sprunge.us/VCYB
>
>Regards,
>Richard
>
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