[vfio-users] Nvidia Code 43 on Fedora 24 host and Windows 10 guest.

[Alex Williamson]

On Wed, 5 Oct 2016 16:35:08 +0200
Thomas Lindroth <thomas.lindroth at gmail.com> wrote:

> On 10/05/2016 09:28 AM, Dawid Osuchowski wrote:> I've ran dd if=NV287MH.2K0 of=strip bs=1 skip=1536, put the ROM file in
> > /usr/share/qemu, run restorecon on it and it started working! I'm so
> > thankful for both of you Alex and Thomas, i've been trying to get it to
> > work for at least 4-5 days and you've helped me in just one day. While
> > we are still here, do you have any recommendations on optimizing the VM
> > so it runs smoothly almost as a native OS and how should i interact with
> > the VM? I've seen an article on
> > https://rokups.github.io/blog/#!pages/kvm-hid.md that made a software
> > KVM switch, would that be good?  
> 
> https://www.redhat.com/archives/vfio-users/2016-September/msg00072.html
> this post explains ways of reducing latency for gaming but be aware that
> reducing latency also tends to reduce performance.

In addition to cpu pinning and isolcpus or cpuset, don't forget about
using hugepages for the VM.  Memory will already be locked in the host
due to the assigned device, but hugepages can eliminate some overhead,
make the hardware work more efficiently and consistently.  Also
remember that CPU sibling threads are not independent from each other,
threading adds X% throughput to a given core (where X may be something
like 20 depending on the workload).  Assigning related threads to
separate tasks means that neither task gets a full CPU.  If you do
assign a pair of threads to a VM, be sure to set the topology to match,
we don't want the VM trying to use each thread as if it was an
independent core.  Clearly, don't overcommit CPUs either, and recognize
that there is some overhead in virtualization , the emulator needs
compute power as well.  You'll quickly start to find out that a
quad-core CPU can be very limiting, especially when you're pairing it
with a beefy graphics card (come on Intel, give us >4-core processors
in the consumer line!.. and ACS too! ;)  Thanks,

Alex