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

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>]

> Yes, both are 2.4.27
> 
> > Also, what happens if you boot xen with 'nosmp' on the Xen
> > command line.
> > 
> 
> There seems to be no change in behaviour. The interrupt layout and count 
> remains roughly the same.
> 
> Do you have any more tips? :)

Please can you try Xen/linux 2.6.9. Also, please can you remind
me of the spec of your machines. 

Ian
 -=- MIME -=- 
On Wed, Oct 27, 2004 at 07:26:10PM +0100, Ian Pratt wrote:
> > On Fri, Oct 22, 2004 at 06:47:35PM +0100, Ian Pratt wrote:
> > > >=20
> > > > We tried to compile xen0 with CONFIG_E1000_NAPI =3D y and got the=
 samre=20
> > > > results between
> > > > two xen dom0 nodes. I am not sure if these interrupts tells anyth=
ing:
> > >=20
> > > 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.
> > >=20
> >=20
> > We tried sending 1 MB and measured:
>=20
> 1MB isn't really very much with a 128KB socket buffer. Do you get
> the same results with larger transfers?
>=20

With 10 MB transfers the results are roughly the same:

native Linux with compiled-in SMP support, single CPU:
        ~ 1365k interrupts
        114 kB/s
Xen0 with "nosmp":
        ~ 1676 k interrupts
        76 kB/s

> > 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
>=20
> It's pretty odd that Xen's taking more interrupts. Are you using
> the same native kernel version as you are for Xen?
>=20

Yes, both are 2.4.27

> Also, what happens if you boot xen with 'nosmp' on the Xen
> command line.
>=20

There seems to be no change in behaviour. The interrupt layout and count =
remains roughly the same.

Do you have any more tips? :)


H=E5vard



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