[vfio-users] Memory allocation with numatune

[Jan Wiele]

Am Freitag, 27. Januar 2017, 08:52:50 CET schrieb Alex Williamson:
> On Fri, 27 Jan 2017 11:58:05 +0100
> 
> Jan Wiele <jan at wiele.org> wrote:
> > Hi,
> > I've two E5-2670 CPUs and want to pin a VM to a node. CPU pinning works
> > fine, however memory allocation seems to happen randomly. Sometimes it is
> > done on node 0, sometimes on node 1.
> > 
> > My VM config: http://pastebin.com/raw/J6trq7gJ
> > I'm on Arch Linux Kernel 4.8.13-1 with libvirt 2.4.0-2
> > 
> > Any ideas?
> 
> Looks like it should work to me.  I've certainly tested this sort of
> setup on RHEL and Fedora in the past and it did the right thing.  

> Your
> vcpupin actually looks a little off though, just like on the host, the
> VM is going to enumerate cores then threads, this is why your numactl
> info shows node0 w/ {0-7,16-23}, node1 w/ {8-15,24-31}, ie.
> {cores,threads}.  By interleaving the node1 pinning as you've done, the
> mapping is off in the VM.  For instance, the guest will think CPU0 and
> CPU6 are threads on the same core, but they're mapped to CPU8 and CPU11
> on the host, which are unrelated.  
Thanks! I will fix that. (I think I did this because of a user, who reported 
slightly better performance, in the old archlinux-vfio-thread)

> I know that doesn't help your
> numatune issue though.

Do you know which part of the system will actually allocate the memory on the 
specified node? Should I see some information about this in the qemu command 
line parameters?