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

[Alexander Petrenz]

Hi,

I guess it's normal that the hugepages reserve memory even if on process is
using them. I have the same situation, but I know having 16GB of memoory, I
don't have enough to give 8GB to the hugepages, 8GB to the VM and 8GB to
the host.
So I think you are fine.

Alex

On Mon, Jan 11, 2016 at 6:52 PM, sL1pKn07 SpinFlo <sl1pkn07 at gmail.com>
wrote:

> 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
>
> _______________________________________________
> vfio-users mailing list
> vfio-users at redhat.com
> https://www.redhat.com/mailman/listinfo/vfio-users
>
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