[vfio-users] Poor Performance and freeze ingame with NVIDIA and 4570K

[Mario Goebbels]

I had issues with freezes in GTA V. The game spawns a whole lot of disk IO,
due to streaming geometry, which is done by default under the QEMU global
lock from what I've read. My naive suspicion was that IO waits were hogging
said lock, getting the VCPUs in a bunch eventually (disk device is an iSCSI
share with bcache on top, cold data has high latency). Once I shoved the
disk IO stuff into its separate thread using iothreads, the freezing
stopped happening. The situation may be similar with Star Citizen. So, my
suggestion is to put your disk IO on an iothread, and also specifying
ioeventfd for both disk and networking.

Also, despite most guides say to disable the Hyper-V stuff, it can actually
do a lot for your framerates. The only problem is that NVidia mucks about,
so you'd need to change the Hyper-V vendor ID*, which only works from
command-line but not libvirt (situation might have changed, I think I've
read bits that NVidia doesn't go Code 43 anymore when it sees the Hyper-V
ID, but I haven't tested). I don't think AMD has any issues with Hyper-V.
If you have an Intel CPU starting from Ivy Bridge-E or Haswell, don't
enable the Hyper-V VAPIC so that it uses APICv instead, which is more
efficient.

Hope that'll help,
-mg

*: hv-vendor-id option on the CPU line, requires QEMU 2.5.

On Thu, Feb 4, 2016 at 2:46 AM, Stibnite <stibnite at protonmail.com> wrote:

> I'm having the same issue, i would suggest posting your xml file, the
> result of uname -a and possibly lspci -nnk.I found switching my disk from
> ide to sata and pinning the vcpu gave a slight boost but games are still
> unplayable. Worth a shot though imo
>
> Sent from ProtonMail <https://protonmail.com>, encrypted email based in
> Switzerland.
>
>
> -------- Original Message --------
> Subject: [vfio-users] Poor Performance and freeze ingame with NVIDIA and
> 4570K
> Local Time: February 3, 2016 5:58 pm
> UTC Time: February 3, 2016 10:58 PM
> From: feadurn at gmail.com
> To: vfio-users at redhat.com
>
> Hi all,
>
> I have done everything I wanted for my VM (except emulate the sound but
> I bought an usb soundcard, as suggested), but I realise my performance
> are quite poor.
> For instance in a game like Insurgency, my FPS are sometime around 30
> which is clearly low for the game (but playable).
>
> More annoying, in game like Star Citizen, not only the performance are
> poor but I have constant freezes, it is like the video freeze (but often
> the sound continue) and then go normal again.
>
> I noticed that it is with when the use of the cpu in Windows reaches
> 100% (but not always).
>
> I don't know if it is caused by the gpu the cpu or both. I have hugepage
> activated and normally the MSI in windows configured too (with a script
> that activate all of them)
>
> I don't really know which output to give you that will be helpful.
>
> Thank you for your help,
>
> Feadurn
>
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