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Increasing VFIO VGA Performance



Hello @gnif ,

I to am having freezing/game crashes even though games run fine otherwise. Been troubleshooting everything from drivers to bad card.

Never thought of a ‘pinning issue or non local memory access’.

I am pinning my CPUs via Libvirt. As far as memory is concerned supposedly all my memory is allocated on the NUMA node associated with the CPUs I have pinned the VM too.

I was just curious if you just meant that CPUs need to be pinned or if pinning can sometimes causes issues and how to troubleshoot that?

This may be getting too off topic sorry if its a loaded question.


Pinning will not affect stability of the VM, only performance.

Correct, please start a new thread. I apologise if this feels like a short answer but please note that my time is limited between the projects I have on at this time and I can not help debug a qemu fault of this nature.


@gnif looks like qemu 3.1 has been released. Not sure if your patch made it, just looking at the pcie.c file. github reveals the file hasn’t been touched for at least 1 year.

In case it didn’t reach the release, can you please provide a clear cut way to apply the patch to qemu 3.1 ? Is there a catch to it ? I’m not entirely literate in C stuff but I can compile stuff from sources (like apache and php). (I’m using Fedora 29, if that matters).


I am sorry but I do not have the time at current to document how to apply the patches, nor do I need to, this information is freely available, see git am for applying patches from a mailbox file.

I am not tracking this patch as to when it will make it into qemu, I do however know it’s being actively worked on as I am seeing updates almost daily by Alex.