[Xen-devel] RE: qemu-dm cpu utilization
thanks for the suggestion.
I defiantly think that the resolution of 800x600
was causing some kind of problem (perhaps the linear framebuffer). When I set
to 1024x768 qemu-dm went down to 10%-12%. Is this the
normal usage that you are seeing?
From: Anthony Liguori [mailto:anthony@xxxxxxxxxxxxx]
Sent: Tue 8/29/2006 7:43 PM
To: McAfee, Tommie M
Subject: Re: qemu-dm cpu utilization
McAfee, Tommie M wrote:
> Using an 8-way ES7000 with 32GB of ram, I'm running xen at changset 11217
> with dom0_mem=3092M as a kernel parameter on a x86_64 hyperviser.
> It appears that qemu is adding too much overhead to
> virtual machines to display graphics.
> If I boot a sles9sp3 domVT in runlevel 5 with vga=0x314 for a graphicalboot,
> and immediately use
> vncviewer simply to watch the virtual machine as it boots,
> qemu-dm consumes 40% cpu as soon as vncviewer is launched and remains that
> way throughout this entire process without settling down when the login
> screen appears.
> Even If I close the console that's viewing the virtual host, qemu-dm remains
> at 40-44%.
Almost everything in the VNC code resets when a guest disconnected
except for the timer. If a client disconnects, the timer routine should
be almost a nop but it's possible that it's somehow causing qemu-dm to
do something funky.
If you delete the timer (and set vs->timer = NULL) in
vnc_client_io_error(), does it reduce the usage?
BTW, if you're using 800x600, I suspect that you may be falling back to
MMIO instead of a linear framebuffer. Try moving to 1024x768 and see if
> When booting the same domVT in runlevel 5 without ever attempting to connect
> to it with
> vncviewer, qemu-dm fluctuated from 1-3% while the host was booting and then
> settled to 0.2% after 4-5 mins. Assuming that the boot process was complete,
> I launched vncviewer and qemu-dm jumped up to a 40-44% range again.
> Lastly I started the same host in runlevel 3 in pure text mode without any
> vga parameters on the kernel line, connected to the virtual machine with
> vncviewer, and watched the machine boot until a login prompt appeared. At
> this point, top showed qemu-dm as using 0% of the cpu. Logging into the
> virtual machine and running 'startx' however sent qemu-dm back up to a 40-
> 44% range.
> Why is qemu-dm consuming so much of the cpu? Why is qemu-dm still high
> even when I close my vncviewer?
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