[Qemu-devel] High dom0 cpu usage using spice

[Fabio Fantoni]

After endless troubles I'm finally approaching to use spice on xen in 
production in place of vnc+rdp.
I have noticed an high dom0 cpu usage by guest's qemu process when spice 
is used (in particular using video streaming).

This is my test system:

Dom0:
Dell Poweredge T310 with cpu xeon X3450 and 12 gb of ram
Debian 7 (Wheezy) 64 bit with kernel from package 
linux-image-3.2.0-4-amd64 version 3.2.54-2 and all dependency packages 
for xen, spice and usb redirection.
Seabios 1.7.4-4, spice 0.12.4-0nocelt2 and usbredir 0.6-2 compiled from 
debian unstable sources.
Latest xen-unstable with some patches 
(https://github.com/Fantu/Xen/commits/hvm-improve.t10) with qemu 2.0.0-rc2.
jpeg-turbo from x2go repository to make spice-server using it and 
decrease cpu usage.

DomU:
windows 7 pro 64 bit with latest gplpv and spice guest tools 0.74
stdvga with 32 mb videoram (qxl for now not working on xen, my latest 
test report of some months ago was without replies)
resolution 1280x768x16bit

Spice client:
good notebook with core i5 cpu with Fedora 20 updated


On start of my tests the dom0 cpu usage was avarage to 60-100% even with 
only one active guest using spice.
Disabling the spice images compression the dom0 cpu usage was up to 30% 
but with drawback of an increased network traffic, specially during 
video streaming.

Can someone advice me to further keep cpu down and/or other optimizations?
Thanks for any reply.