[vfio-users] threadripper slowness

[gamanakis at gmail.com]

You could probably get rid of all the lag you experience. Possibly qemu 4.0
provides better topology to the guest. Generally Threadripper CPUs have 2
NUMA nodes, and you would want to pin the vcpus of the guest to one NUMA
node, and also allocate RAM from the same NUMA node. You would also have to
make sure the passthrough devices sit on corresponding PCIe lanes which that
NUMA node controls. There is lots of good info in reddit.com/r/vfio. Please
also provide your xml file (or script), and what you use as a virtualized
hard drive. Is it a passthrough NVMe, or virtio-scsi? In the latter case you
should also pin iothreads on the same NUMA node as everything else.
You can see the topology and NUMA nodes of your cpu by running lstopo. 

I am eager to see a configuration that uses both NUMA nodes of a
Threadripper CPU in one guest with minimal latency.

> -----Original Message-----
> From: vfio-users-bounces at redhat.com <vfio-users-bounces at redhat.com>
> On Behalf Of Roger Lawhorn
> Sent: Sunday, August 11, 2019 9:31 PM
> To: vfio-users at redhat.com
> Subject: Re: [vfio-users] threadripper slowness
> 
> Hello,
> 
> Just wanted to mention that I got rid of a lot of the lag by compiling
qemu 4.0.
> I dod not know if its a threadripper issue or not.
> The lag directly coincides with hard drive access.
> No hard drive access, no game lag.
> I have redhat virtio drivers installed for the hard drive and the nic.
> Are these drivers intel only?
> They are left only from my i7-4940mx processor install.
> 
> 
> On 8/9/19 11:51 AM, Roger Lawhorn wrote:
> > Hello.
> > I am new to the list.
> > I have been doing gpu passthrough for almost 5 years now with a i7
> > 4940mx cpu on a msi gt70 laptop.
> >
> > My new PC build is:
> > MSI x399 carbon pro motherboard : bios xxxxxx.1c0 : svm=enabled:
> > iommu=enabled
> > Threadripper 2920 12 core
> > Radeon pro duo R9 Fury X
> > Nvidia 980 TI OC
> >
> > I was unable to passthrough the nvidia card due to it not getting past
> > the "Running option rom..." message when debugging.
> >
> > The Radeon passed through with flying colors.
> >
> > The issue:
> > I used the radeon to run triple A games in linux using steam for linux
> > and proton. No problems.
> >
> > In Windows 7 in qemu I have passed all 24 cpus to it.
> > They max out to 80% while playing the same triple A games and the
> > games lag.
> > I have never had this issue before.
> >
> > Admittedly I am using the same script I used on the i7 to get going.
> > I had to remove threads from the -smp switch and use cores only.
> >
> > I also removed the kvm=off which is used for nvidia cards.
> >
> > I am looking for links to articles or direct info on what to do to
> > optimize the cpus.
> > When not lagging the radeon performs extremely well.
> >
> > I am concerned that perhaps kvm is not being used.
> >
> >
> > Thanks
> >
> > _______________________________________________
> > vfio-users mailing list
> > vfio-users at redhat.com
> > https://www.redhat.com/mailman/listinfo/vfio-users
> >
> 
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