RE: less cores more iops / speed

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> > I've noticed something really interesting.
> >
> > I get 5000 iops / VM for rand. 4k writes while assigning 4 cores on a
> > 2.5 Ghz Xeon.
> >
> > When i move this VM to another kvm host with 3.6Ghz i get 8000 iops
> > (still 8
> > cores) when i then LOWER the assigned cores from 8 to 4 i get
> > 14.500 iops. If i assign only 2 cores i get 16.000 iops...
> >
> > Why does less kvm cores mean more speed?
> 
> There is a serious bug in the kvm vhost code. Do you use virtio-net with
> vhost?
> 
> see: http://lists.nongnu.org/archive/html/qemu-devel/2012-
> 11/msg00579.html
> 
> Please test using the e1000 driver instead.

Or update the guest kernel (what guest kernel do you use?). AFAIK 3.X kernels does not trigger the bug.

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