Re: does anyone run guests for more than 5 minutes? (virtio-net perf anomaly)

[Marcelo Tosatti <mtosatti@redhat.com>]

On Fri, Mar 06, 2009 at 08:26:33AM -0700, Alex Williamson wrote:
> On Thu, 2009-03-05 at 21:25 -0700, Alex Williamson wrote:
> > On Thu, 2009-03-05 at 21:04 -0300, Marcelo Tosatti wrote:
> > > On Tue, Mar 03, 2009 at 01:13:41PM -0700, Alex Williamson wrote:
> > > > Any guesses as to what might be going on?  Can anyone reproduce?  I'm
> > > > hoping that I'm doing something dumb, but can't figure out what it is.
> > > > The system is running v2.6.29-rc6-121-g64e7130 in the guest,
> > > > v2.6.29-rc6-123-gbd7b3b4 on the host, kvm module kvm-84-620-g5bffffc and
> > > > userspace kvm-84-95-gea1b668.  Thanks,
> > > 
> > > Nope. Collect kvm_stat -l before/after the slowdown?
> > 
> > Attached.  This shows about 1 minute of data before the slowdown and a
> > dramatic change starting around the 80th row.  Thanks,
> 
> For a bit easier consumption, here's a google spreadsheet and chart of
> what appear to be the interesting columns:
> 
> http://spreadsheets.google.com/pub?key=pdwpc4VwMbjWxyQfvw8AEYg
> 
> Alex

irq_injection goes up significantly. Is it virtio_net generating more
interrupts? Check the rate of irq's generated by hw/virtio-net.c and
compare that with rate seen in /proc/interrupts inside the guest?