RE: [Xen-ia64-devel] kernel build performance data with dom0_VP modeopen

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> For dom0vp model, VHPT size is reduced to 64KBytes to avoid
> triggering software lock detection.
> For P=M model, its size remain 64MB.
> It would be interesting to measure on P=M model with 64KBtyes 
> VHPT size.
> (Edit VHPT_SIZE_LOG2 in xen/include/asm-ia64/vhpt.h)

Yes, having a VHPT that is 1024x smaller is likely
to make a big difference in performance.  I'm surprised
it isn't worse!

I agree it would be interesting to measure P==M with
the smaller vhpt (Jingke, is this a measurement you
could easily make on your system?), but since we are
definitely moving ahead with VP it would be good to
look forward rather than back.

Can you explain in more detail about the software lock
detection and why a 64KB VHPT avoids it?  Any ideas on
how to get to a larger VHPT (not necessarily as large
as 64MB)?

Thanks,
Dan

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