[Spice-devel] troubleshooting performance and latency issues?

[Daniel Pocock]

Hi,

I've observed some latency issues, for example, changing focus from one
terminal to another is a bit sluggish.  Typing isn't too bad.
Interaction with the sliding GNOME unlock screen and drawing the desktop
after unlock is painfully slow.

The virtual server I connect to runs Debian jessie and GNOME 3 desktop,
it is a default install:
Xorg = 2:1.16.4-1
xserver-xorg-video-qxl = 0.1.1-2+b1
spice-vdagent = 0.15.0-1.2

I'm monitoring the latency of the connection to the KVM/libvirt/SPICE
server with Smokeping, average ping time is about 0.8ms, no packet loss.


I've setup the KVM/libvirt/SPICE host like this:
Debian stretch
Kernel = 4.9.13
libspice-server1 = 0.12.8-2.1
libvirt0 = 3.0.0-3


I've tried using both virt-manager and virt-viewer as clients on a
Debian jessie system, connecting over SSH to the KVM host, these are the
client versions:

virt-manager = 1:1.0.1-5
virt-viewer = 1.0-1

I noticed it appears a little better with virt-manager than virt-viewer,
should there be any difference between these two products if they both
use the same protocol?

Can I do anything to tweak the .ssh/config to make it better?  It
occurred to me that adding "IPQoS lowdelay" might be useful as it
defaults to "throughput" for non-interactive connections.  Maybe
virt-manager should add that on the ssh command line?

Is there any way to see SPICE latency statistics in the virt-manager GUI?

Would any other SPICE viewer make a difference?

Are there any changes I should make to the GNOME desktop configuration
to make it work better through SPICE?  I've heard people comment on
changing to fvwm.

Can anybody make any other suggestions?

Regards,

Daniel