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Re: [libvirt] Qemu/KVM is 3x slower under libvirt (due to vhost=on)

On 09/28/11 14:56, Richard W.M. Jones wrote:
On Wed, Sep 28, 2011 at 12:19:09PM +0200, Reeted wrote:
Ok that seems to work: it removes the vhost part in the virsh launch
hence cutting down 12secs of boot time.

If nobody comes out with an explanation of why, I will open another
thread on the kvm list for this. I would probably need to test disk
performance on vhost=on to see if it degrades or it's for another
reason that boot time is increased.
Is it using CPU during this time, or is the qemu-kvm process idle?

It wouldn't be the first time that a network option ROM sat around
waiting for an imaginary console user to press a key.


Of the two qemu-kvm processes (threads?) which I see consuming CPU for that VM, one is at about 20%, the other at about 10%. I think it's doing something but maybe not much, or maybe it's really I/O bound and the I/O is slow (as I originarily thought). I will perform some disk benchmarks and follow up, but I can't do that right now...
Thank you

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