Re: Xen & I/O in clusters - problems! New Information

[Håvard Bjerke <Havard.Bjerke@idi.ntnu.no>]

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We're getting these results in domain 0, not in a VM. As I understand, BVT or apropos scheduling do not apply in domain 0?

Håvard

On Wed, Oct 27, 2004 at 07:40:27PM +0100, Mark A. Williamson wrote:
> Just a thought: you are using the BVT scheduler, right?  We haven't tested 
> performance with the other schedulers recently but we know something goes 
> wrong for IO intensive domains on Atropos.
> 
> Mark
> 
> On Wednesday 27 Oct 2004 19:26, Ian Pratt wrote:
> > > On Fri, Oct 22, 2004 at 06:47:35PM +0100, Ian Pratt wrote:
> > > > > We tried to compile xen0 with CONFIG_E1000_NAPI = y and got the samre
> > > > > results between
> > > > > two xen dom0 nodes. I am not sure if these interrupts tells anything:
> > > >
> > > > It's the different rate at which the eth0 interrupt counts go up
> > > > during your bandwidth tests that is interesting. e.g. poll it
> > > > once a second during the test.
> > >
> > > We tried sending 1 MB and measured:
> >
> > 1MB isn't really very much with a 128KB socket buffer. Do you get
> > the same results with larger transfers?
> >
> > > non-SMP native Linux:
> > >  ~ 130k interrupts
> > >  114 kB/s
> > > native Linux with compiled-in SMP support, single CPU:
> > > 	~ 140k interrupts
> > > 	114 kB/s
> > > Xen0:
> > > 	~ 180k interrupts
> > > 	80 kB/s
> >
> > It's pretty odd that Xen's taking more interrupts. Are you using
> > the same native kernel version as you are for Xen?
> >
> > Also, what happens if you boot xen with 'nosmp' on the Xen
> > command line.
> >
> > We've got Xen tcp performance results from a bunch of machines,
> > and dom0 to dom0 performance has always been almost identical to
> > native for 1500 byte MTU packets.
> >
> >
> > Ian
> >
> >
> >
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