Re: windows domU disk performance graph comparing hvm vs stubdom vs pv drivers

[Daniel Stodden <daniel.stodden@citrix.com>]

On Fri, 2010-02-19 at 19:50 -0500, Keith Coleman wrote:
> On Fri, Feb 19, 2010 at 7:08 PM, Daniel Stodden
> <daniel.stodden@citrix.com> wrote:
> > On Fri, 2010-02-19 at 17:41 -0500, Keith Coleman wrote:
> >
> >> This graph shows the performance under a webserver disk IO workload at
> >> different queue depths. It compares the 4 main IO methods for windows
> >> guests that will be available in the upcoming xen 4.0.0 and 3.4.3
> >> releases: pure HVM, stub domains, gplpv drivers, and xcp winpv
> >> drivers.
> >
> > Cool, thanks. If I may ask, what exactly did you run?
> 
> iometer
> 
> >> The gplpv and xcp winpv drivers have comparable performance with gplpv
> >> being slightly faster. Both pv drivers are considerably faster than
> >> pure hvm or stub domains. Stub domain performance was about even with
> >> HVM which is lower than we were expecting. We tried a different cpu
> >> pinning in "Stubdom B" with little impact.
> >
> > Is this an SMP dom0? A single guest?
> 
> Dual core server with dom0 pinned to core 0 and a single domU pinned
> to core 1. Stubdom was pinned to core 0 then core 1.

I don't see why stubdom would be faster in either configuration. Once
you're through DM emulation, there's plenty of cycles to spend waiting
for I/O completion. So dom0 won't mind spending them on qemu either.

Daniel