[vfio-users] Enable Hugepages, but is not used by VM

[sL1pKn07 SpinFlo]

Hi

I have add hugepages on my VM. but when launch the VM and run 'grep
Huge /proc/meminfo' on the host, the value is the same when the VM is
close

i'm not sure if i missing any step

in /etc/libvirt/qemu.conf:

hugetlbfs_mount = "/dev/hugepages"

in the VM XML:

  <memoryBacking>
   <hugepages/>
 </memoryBacking>

in my system, Hugepages is mounted by systemd:
└───╼  systemctl |grep huge
dev-hugepages.mount

                loaded active mounted   Huge Pages File System

└───╼  mount |grep huge
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)

└───╼  find /dev/hugepages
/dev/hugepages
/dev/hugepages/libvirt
/dev/hugepages/libvirt/qemu

└───╼  ls -R /dev/hugepages
/dev/hugepages:
total 0
drwxr-xr-x  3 root root    0 ene 11 17:14 .
drwxr-xr-x 19 root root 3880 ene 11 17:14 ..
drwxr-xr-x  3 root root    0 ene 11 17:14 libvirt

/dev/hugepages/libvirt:
total 0
drwxr-xr-x 3 root root 0 ene 11 17:14 .
drwxr-xr-x 3 root root 0 ene 11 17:14 ..
drwxr-xr-x 2 root kvm  0 ene 11 17:33 qemu

/dev/hugepages/libvirt/qemu:
total 0
drwxr-xr-x 2 root kvm  0 ene 11 17:33 .
drwxr-xr-x 3 root root 0 ene 11 17:14 ..

└───╼  cat /etc/sysctl.d/10-kvm.conf
vm.nr_hugepages=6144

VM OFF
└───╼  grep Huge /proc/meminfo
AnonHugePages:  13309952 kB
HugePages_Total:    6144
HugePages_Free:     6140
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

VM ON (with some programs open)
└───╼  grep Huge /proc/meminfo
AnonHugePages:  13309952 kB
HugePages_Total:    6144
HugePages_Free:     6140
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

archlinux
Linux sL1pKn07 4.3.3-2-ARCH #1 SMP PREEMPT Wed Dec 23 20:09:18 CET
2015 x86_64 GNU/Linux
libvirt from git 6e27701
qemu from git ccd54b6 (from Gerd Hoffmann's branch (linux-imput))
Windows10 guest installed before add hugepages options

greetings