[vfio-users] problem with hugepages and sound

[Tomasz Jan Góralczyk]

On 04/11/15 20:15, Janusz wrote:
> Hi,
> I have two questions,
> Sometimes I have some short freezes and fps drops in GTA 5, so I wanted
> to try hugepages if it would give me better perfornance, but in fact it
> gave me -10 fps and drops to 20-30 fps (while without it I have 60 with
> drops to 40). Did anyone experiecned worst performance with hugepages?
> maybe I am doing something wrong?
> my script: https://bpaste.net/show/9089719cbef8
> 
> Second question, I know this is vfio group but I don't know where else
> would be better to ask, becauseeverywhere where I asked, no one know how
> to fix it. I am using pulseaudio and I have some audio glitches, some
> crackles, don't know exactly how to describe it... It looks like VM is
> affecting my audio even before OVMF loads (starting VM) and it happens
> the whole time when I get some sound from VM. anyone know what can cause
> this? I tried different soundhw, sometimes I didn't get any disortion in
> the sound, but then the sound was behind something like 1 second. I have
> the same frequency in pulsaudio set like in windows settings. I even
> bought usb sound card, to passthrough it and redirect this sound from VM
> into my main sound card - poor quality. also tried streaming from
> windows by linco, ssh and pacat - got some delays, port of pulseaudio
> for windows - didn't managed to make it work... I know there is one more
> alternative - Jackd, but maybe someone have idea how to fix it before I
> start looking in jackd configuration...
> I also tried without pulseaudio on host, just alsa, and didn't helped

I also had the same problem with audio and the only way I could fix it
was by passing through my onboard sound card via vfio. I had to `rmmod`
the snd_hda_intel module before binding the sound card's vfio group to
make it work. Obviously, it's not ideal since the card can't be shared
between the host and the guest, but you already have an USB soundcard,
so why not use that on the host? After I'm done with the guest, I shut
it down, unbind the sound card's vfio group and `modprobe` the
snd_hda_intel module to get audio back up on the host. Note that
Pulseaudio won't let you unload your sound card's kernel module, while
it's running.

I have an ASUS Z97 board and a 4790k, so ymmv.

> 
> My hw:
> msi z170a m7, i7 6700k, r9 290
> 
> 
> Thanks
> 
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> 

-- 
 Tomasz Jan Góralczyk
 tomg at fastmail.uk
 PGP: 0x9A1735E96B636FC1

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