Re: [Qemu-devel] Windows slow boot: contractor wanted

[Avi Kivity]

On 08/20/2012 04:56 PM, Richard Davies wrote:

> We're running host kernel 3.5.1 and qemu-kvm 1.1.1.
> 
> I hadn't though about it, but I agree this is related to cpu overcommit. The
> slow boots are intermittent (and infrequent) with cpu overcommit whereas I
> don't think it occurs without cpu overcommit.
> 
> In addition, if there is a slow boot ongoing, and you kill some other VMs to
> reduce cpu overcommit then this will sometimes speed it up.
> 
> I guess the question is why even with overcommit most boots are fine, but
> some small fraction then go slow?

Could be a bug.  The scheduler and the spin-loop handling code fight
each other instead of working well.

Please provide snapshots of 'perf top' while a slow boot is in progress.

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