On Thu, 2009-07-02 at 12:41 +0300, Avi Kivity wrote:

quoted text
> On 07/02/2009 08:48 AM, Avi Kivity wrote:

> >> HOST time (make -j12&&   make -j12 modules) with no guest running

> >> ----------------------------------------------------------------

> >> real    6m50.936s

> >> user    29m12.051s

> >> sys    5m50.867s

> >>

> >

> > 35 minutes cpu run on 7 minutes real time, so scaling 1:7.  User time

> > almost the same, system time different but not enough to account for

> > the large difference in run time.

> >

> > I'm due to get my own Nehalem next week, I'll try to reproduce your

> > results here.

> >

>

> I reproduced this on a 2x4 barcelona, I get 6.6x scaling on the guest

> compared to your 7.2x on the host.  This is with a kvm.git host kernel.

> Once thing that changed is an improvement in cfq with multiple threads;

> try setting the host io scheduler for /dev/sdb to deadline (together

> with dropping -usbdevice tablet).

Haven't followed the thread in great detail, but has anyone tried

putting the virtio disk back into rotational mode?
See also:
  https://bugzilla.redhat.com/509383
and:
  http://lkml.org/lkml/2008/10/27/84
Cheers,

Mark.
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