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

[Richard Davies]

Brian Jackson wrote:
> Richard Davies wrote:
> > The host in question has 128GB RAM and dual AMD Opteron 6128 (16 cores
> > total). It is running kernel 3.5.1 and qemu-kvm 1.1.1.
> >
> > In this morning's test, we have 3 guests, all booting Windows with 40GB RAM
> > and 8 cores each (we have seen small VMs go slow as I originally said, but
> > it is easier to trigger with big VMs):
> >
> > pid 15665: qemu-kvm -nodefaults -m 40960 -smp 8 -cpu host,hv_relaxed \
> >   -vga cirrus -usbdevice tablet -vnc :99 -monitor stdio -hda test1.raw
> > pid 15676: qemu-kvm -nodefaults -m 40960 -smp 8 -cpu host,hv_relaxed \
> >   -vga cirrus -usbdevice tablet -vnc :98 -monitor stdio -hda test2.raw
> > pid 15653: qemu-kvm -nodefaults -m 40960 -smp 8 -cpu host,hv_relaxed \
> >   -vga cirrus -usbdevice tablet -vnc :97 -monitor stdio -hda test3.raw
>
> What memory options have you tried? (KSM, hugepages, -mem-preallocate)?

The host kernel has KSM and CONFIG_TRANSPARENT_HUGEPAGE=y and
CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y.

Our qemu-kvm command lines are as above, so we aren't using -mem-prealloc.
We'll try that.

> Is this only with 2008? (is that regular? R2?)

It is intermittent. We definitely see it with 2008 R2, and I believe with
2008 as well. We don't have many customers running earlier versions of
Windows.

>    Have you tried any of the hyperv features/hints?

We have tried "-cpu host" and "-cpu host,hv_relaxed" as above, which both
exhibit the bug.

What other hyperv options do you think we should try?

Richard.