Re: [Xen-users] SMP enabled Dom0 or not?

[Stefan de Konink <skinkie@xxxxxxxxx>]

Todd Deshane schreef:
> Hi Stefan,
>
> On Sat, Jun 14, 2008 at 7:27 PM, Stefan de Konink <skinkie@xxxxxxxxx 
> <mailto:skinkie@xxxxxxxxx>> wrote:
>     Hello,
>
>
>     I wonder if the performance of a Xen machine can be increased by
>     disabling SMP in the Linux kernel by default, basically having one
>     of the 8 processors tied to dom0.
>
>     In my scenario I use NFS or iSCSI as file backend. Looking at NFS
>     there will be a lot of tapdrives, while in the iSCSI scenario there
>     is fewer overhead in userspace processes.
>
>     Could anyone give me a hint on the performance increase or decrease
>     using SMP vs Uniprocessor?
>
>
> In the original "Xen and the Art of Virtualization" they actually 
> disabled SMP and had better IO performance. I don't know if this is 
> still true.
> Take a look at:
> http://research.microsoft.com/~tharris/papers/2003-sosp.pdf
> www.clarkson.edu/class/cs644/xen/files/repeatedxen-usenix04.pdf 
> <http://www.clarkson.edu/class/cs644/xen/files/repeatedxen-usenix04.pdf>
Now I guess in 2003 there was no concept like tapdisk yet. I'll see if I 
can get a clean benchmark. Of 32 VMs doing the same task, SMP vs non-SMP.


Stefan

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