Re: [Libvir] PATCH: Improve performance on Xen

[Daniel Veillard <veillard redhat com>]

On Fri, Aug 10, 2007 at 02:33:28PM +0100, Daniel P. Berrange wrote:
> On Fri, Aug 10, 2007 at 06:39:56AM -0400, Daniel Veillard wrote:
> >   Well if you have 100 guests, that may be slower, but in the average situation
> > of only a couple of guests, it could be a real speedup. The problem is that
> > a lot of domain may accumulate in xenstore /local/domain even if they are
> > not running, both implementation are likely to have completely different 
> > behaviour based on the context. But from a cache locality perspective hitting
> > xenstore may scale way better under loaded machines, so it may prove faster
> > even on machines with hundreds of domains. Doing a fair performance comparison
> > may prove really hard.
> 
> Actually the /local/domain/[ID] subtree is guarenteed to only contain running 
> VMs. The /vm/[UUID] subtree is where cruft accumulates over time, so its safe 
> to rely on info in the former, but not the latter

Ah, right, I somehow remembered some nastyness there, but it wasn't precise :-)

Daniel

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