Anthony,
>If you delete the timer (and set vs->timer = NULL) in
>vnc_client_io_error(), does it reduce the usage?
setting vs->timer=NULL causes qemu-dm to segfault when I launch vncviewer
to view the virtual host. Here is a snippet of the strace results:
ioctl(13, EVIOCGKEYCODE, 0x7fffff904ee0) = 0
select(17, [6 9 11 13 16], [], [], {0, 10000}) = 1 (in [13], left {0, 10000})
read(13, "\34\0\0\0", 4) = 4
write(13, "\34\0\0\0", 4) = 4
clock_gettime(CLOCK_MONOTONIC, {87584, 18585008}) = 0
clock_gettime(CLOCK_MONOTONIC, {87584, 18684008}) = 0
clock_gettime(CLOCK_MONOTONIC, {87584, 18783008}) = 0
ioctl(13, EVIOCGKEYCODE, 0x7fffff904ee0) = 0
select(17, [6 9 11 13 16], [], [], {0, 10000}) = 1 (in [13], left {0, 10000})
read(13, "\34\0\0\0", 4) = 4
write(13, "\34\0\0\0", 4) = 4
clock_gettime(CLOCK_MONOTONIC, {87584, 31583008}) = 0
clock_gettime(CLOCK_MONOTONIC, {87584, 31685008}) = 0
clock_gettime(CLOCK_MONOTONIC, {87584, 31785008}) = 0
clock_gettime(CLOCK_MONOTONIC, {87584, 57104008}) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
Process 17185 detached
According to strace, the timers account for a lot of qemu-dm's activity.
Is this polling a bit excessive?
Tommie McAfee
Xen-Testing
-----Original Message-----
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
that helps.
Regards,
Anthony Liguori
>
> 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?
>
> Tommie,
> Xen Test Team
> Unisys
>
>
>
> ------------------------------------------------------------------------
>
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