Re: Libvirt qemu-system-x86_64 on ppc64le no multi threading
On Mon, Aug 03, 2020 at 03:35:49PM +0100, Daniel P. Berrangé wrote:
On Mon, Aug 03, 2020 at 01:45:45PM +0000, Kim-Norman Sahm wrote:
> hi,
>
> i’m running Debian 10 on POWER9 and would like to spawn x86_64 emulated VMs.
> The virtual machine is configured to run with 8 vpus but it’s very slow.
> On the host you can see that the qemu-system-x86_64 process is using just one core!
>
> Ppc64le guests are using multi cores, so its looks like an config problem or
software bug with the x86 emulator.
snip
> Does anybody knows this problem?
You've not mentioned what QMEU version or what libvirt version you have.
Actually this doens't matter.
Historically though emulation was single threaded. Only with MTTCG has
it become multi-threaded and thus able to use all cores for vCPUs. THat
is a few years old now though, so most distros should have MTTCG in some
form or another if reasonably up2date.
x86_64 guest on ppc64 host simply cannot use MTTCG at all, so will always
be restricted to 1 thread. If you want concurrency you'll need to run on
a real x86_64 host.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|