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Re: [Xen-devel] HYBRID: PV in HVM container

On Thu, Jul 28, 2011 at 12:34:42PM +0100, Stefano Stabellini wrote:
> On Thu, 28 Jul 2011, Mukesh Rathor wrote:
> > Hi folks,
> > 
> > Well, I did some benchmarking and found interesting results. Following
> > runs are on a westmere with 2 sockets and 10GB RAM.  Xen was booted
> > with maxcpus=2 and entire RAM. All guests were started with 1vcpu and 2GB 
> > RAM. dom0 started with 1 vcpu and 704MB. Baremetal was booted with 2GB 
> > and 1 cpu.  HVM guest has EPT enabled. HT is on.
> > 
> > So, unless the NUMA'ness interfered with results (using some memory on 
> > remote socket), it appears HVM does very well. To the point that it
> > seems a hybrid is not going to be worth it. I am currently running
> > tests on a single socket system just to be sure.
> > 
> The high level benchmarks I run to compare PV and PV on HVM guests show
> a very similar scenario.
> It is still worth having HYBRID guests (running with EPT?) in order to
> support dom0 in an HVM container one day not too far from now.

I am just wondering how much dom0 cares about this? I mean if you use
blkback, netback - etc - they are all in the kernel. The device drivers
are also in the kernel.

Based on Mukeshs's results the PVonHVM work you did really paid
itself off for guests. The numbers are even better than baremetal .. which
I am bit surprised - maybe the collecting of the data (gettimeofday) is
not the best?

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