RE: [Xen-devel] Performance issuses with Splash2 applications on XEN

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

Is this using SMP guests from the unstable tree? If so, there's some
serious scheduler issues which are currently being worked on -- its
certainly not ready for serious benchmarking (though this might be
useful application for us to use for tuning purposes).

How many CPUs has the machine you're running on? How many virtual CPUS
does the guest have?

Ian

> -----Original Message-----
> From: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of 
> jessie smart
> Sent: 02 February 2005 20:23
> To: xen-devel@xxxxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] Performance issuses with Splash2 
> applications on XEN
> 
> I am running one of the applications from the Stanford 
> splash2 application suite ( 
> http://www-flash.stanford.edu/apps/ ) and getting an 
> unexpected (~5x) performance decrease in domU when specifying 
> more than 1 processor in the application.   dom0 seems to 
> handle this fine.
> 
>  
> 
> Specificly I am seeing this on the water-nsquared app.  I am 
> not going to give my machine config here (if you need them 
> please ask) just the differences in runtime and the 
> parameters of the app.
> 
>  
> 
>  
> 
> all are running single processor & 1GB RAM
> 
> (times reported as real/user/system, in seconds)
> 
>  
> 
> water-nsquared 64 processors 8000 molecules
> 
>  
> 
> baseline (non-xen) 72.20/78.80/0.17 
> 
> Dom0                   77.76/77.17/0.16
> 
> DomU                   357.24/357.04/0.018
> 
>  
> 
> water-nsquared 1 processor 8000 molecules
> 
>  
> 
> baseline (non-xen) 73.16/72.75/0.15 
> 
> Dom0                   72.75/72.37/0.02
> 
> DomU                   66.07/66.04/0.02
> 
>  
> 
>  
> 
> I have disabled the /lib/tls.
> 
>  
> 
> I am hoping that someone here with a little more experience 
> with Xen can help me try to explain this.  Any input would be 
> greatly appreciated.
> 
>  
> 
> Jessie
> 
> jessiesmart354@xxxxxxxxx
> 
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