Xen users - Apr 2006 - Xen Performance with Charm++

Dear All,

I am doing a performance study on Xen, and we are deploying Charm++ 
parallel runtime library as part of our applications. However, we 
observed a 20% slow down in Xen kernel that was not observed with MPICH. 
It is very important for us to understand why this overhead is happening.

I am guessing that is caused due to the higher cost of system calls like 
fork and exec, since Charm++ deploy a dynamic load-balancing algorithm 
that relocates jobs across the cluster, and thus using extensively the 
fork and exec syscalls. However, it is surprising for me that the 
overhead is as high as 20%.

My question is about the cost of fork and exec in the new Xen v3? My 
guess is that they are higher than those published for v1 in Xen Art of 
virtualization paper.

Thank you,
Lamia Youseff



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Lamia M.Youseff wrote:
> Dear All,
>
> I am doing a performance study on Xen, and we are deploying Charm++ 
> parallel runtime library as part of our applications. However, we 
> observed a 20% slow down in Xen kernel that was not observed with 
> MPICH. It is very important for us to understand why this overhead is 
> happening.
>
> I am guessing that is caused due to the higher cost of system calls 
> like fork and exec, since Charm++ deploy a dynamic load-balancing 
> algorithm that relocates jobs across the cluster, and thus using 
> extensively the fork and exec syscalls. However, it is surprising for 
> me that the overhead is as high as 20%.
>
> My question is about the cost of fork and exec in the new Xen v3? My 
> guess is that they are higher than those published for v1 in Xen Art 
> of virtualization paper.
You''ll have to expand a bit more on the particulars of your setup.  If 
you''ve got domUs running and your using bridging with any significant 
network load, you can expect a pretty good amount of CPU is going to be 
going to that.

Regards,

Anthony Liguori
> Thank you,
> Lamia Youseff
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users

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