DmaBuf + Spice-gtk gl + UHD 630: win10 guest, mouse lag/delay

[shunlir]

Is client mode mouse supported currently?
(EDIT: checked trace of qemu, client mouse mode is enabled and being used, but there is definitely something wrong with the cursor/mouse update )
(EDIT2: client mouse mode is being used (absolute mouse position), but it's server-rendered cursor)
I can feel obvious mouse lag/delay in the spice/gtk console, but mouse in RDP is very smooth.

• Coffee Lake (i5 8400, UHD Graphics 630 pci id: 8086:3e92)
• kernel 5.4.23-gentoo
• qemu 4.2.0 + spice 0.14
• spice-gtk 0.37
• spice agent (in guest) 0.10.0.0
  My libvirt config:

...
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
...
    <graphics type='spice'>
      <listen type='none'/>
      <gl enable='yes' rendernode='/dev/dri/by-path/pci-0000:00:02.0-render'/>
    </graphics>
...
    <video>
      <model type='none'/>
    </video>
...
  <qemu:commandline>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.ramfb=on'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.driver=vfio-pci-nohotplug'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.x-igd-opregion=on'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.xres=1920'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.hostdev0.yres=1080'/>
  </qemu:commandline>

[ChristophSchmidpeter]

@shunlir I don't experience a mouse lag by itself, but have low frame rate as described in #35, even though I have recompiled qemu as described there with 60 instead of the default 30 fps. Maybe that is what you are experiencing as well.

[shunlir]

@tituslabienus, I can confirm, in my case, client mode mouse (absolute mouse position) is working, but the cursor is server-rendered, maybe together with the screen in dma-buf.
I think increase frame rate (#35) could reduce mouse lag if the dma-buf can give 60fps, I'll give it a try.

[shunlir]

workaround: Mouse lag improved by recompiling qemu with GUI_REFRESH_INTERVAL_DEFAULT changed to 17. (#35)

[cxdong]

Is this still a valid issue? If not, would like to close this issue as no update for a long time.

[tomlankhorst]

Seems to me that this problem keeps occurring since GUI_REFRESH_INTERVAL_DEFAULT is still a fixed value in QEMU.

[nikp123]

Seems to me that this problem keeps occurring since GUI_REFRESH_INTERVAL_DEFAULT is still a fixed value in QEMU.

Time to write a series of patches to QEMU mainline. I'll try getting it working (hopefully). The last time it was GTK using that value, now it's SPICE. let's say I already dug too deep ;)