[Xen-devel] Re: Poor performance on HVM (kernbench)

[Anthony Liguori <anthony@xxxxxxxxxxxxx>]

Todd Deshane wrote:
> As an update, Xen HVM on Xen 3.2 on Ubuntu 8.04 from packages:
>
> Average Optimal load -j 4 Run (std deviation):
> Elapsed Time 954.4 (4.95457)
> User Time 441.744 (2.56251)
> System Time 506.018 (7.45156)
> Percent CPU 99 (0)
> Context Switches 160222 (1113.68)
> Sleeps 37604.8 (182.796)
>
> This is actually more what would be expected of Xen 3.2 right?
It's pretty close to what I've seen.  In my experience with shadow2, xen 
pv is about twice as fast with kernbench.  You're results for a pv were:
Elapsed Time 446.876 (0.130115)

So this result is a bit higher than what I've seen, but certainly within 
the realm of possibility.
> Xen 3.3 should be an improvement with shadow3 right?
I know it is for Windows, but there's always the possibility that it has 
caused a regression in Linux performance.
Regards,

Anthony Liguori

> Should I need to adjust the shadow_memory parameter for the guest?
>
> I'm going to try Xen 3.2.1 from source next.
>
> Todd

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