Re: [Xen-devel] poor domU VBD performance.

[Andrew Theurer <habanero@xxxxxxxxxx>]

On Thursday 31 March 2005 16:36, Ian Pratt wrote:
> >       reqsze    MB/sec    svcmt
> >
> > xenU    16k     6266.67   1.25
> >         32k    12618.67   1.20
> >         64k    25002.67   1.28
> >        128k    49322.67   1.35
> >        256k    58538.67   3.15
> >
> > xen0    16k    13818.67   1.15
> >         32k    27573.33   1.16
> >         64k    54784.00   1.16
> >        128k    58581.33   2.18
> >        256k    58453.33   4.38
> >
> > noXen   16k    58679.19   0.27
> >     32k    58453.33   0.54
> >     64k    58713.04   1.08
> >        128k    58174.09   2.17
> >        256k    58820.07   4.36
>
> These figures for xen0 are interesting. It's odd that we tail off so
> badly for short requests. What interrupt rates are occuring when you
> do these tests?

I just ran again, and for some reason it looks fine now...  I have no 
idea what I did to get the lower numbers initially, perhaps an 
inadvertant IO scheduler change.  Service commit times are .28ms and I 
can drive ~58MB/sec with just 16k requests on xen0.  I'll do some more 
tests to get a more consistent picture.

-Andrew

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