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

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

> 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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