[Xen-ia64-devel] RE: SMP patch

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

> > 2) Is there a reason you reduced the VHPT size 4x?  It
> >    appears to have slowed performance down noticably
> >    (about 1%).
> I tried to boot with 6 procs, and the boot failed because the 
> xenheap is to 
> small.  Please, restore the VHPT size.

I see.  The early physical memory allocation for Xen was
written long ago and is probably still very primitive and
restrictive. It definitely needs some work to handle
new demands such as more CPUs and more domains.

It would be useful to understand how much physical memory
is needed per processor (and also per domain).  Shrinking
the VHPT is just a short-term solution; you will just run
out of xenheap when you add a few more processors, correct?

Perhaps a better short-term solution (than hard-coding a
smaller VHPT) would be to use a xen command-line flag
"vhptsize=24" so this can be changed at boot-time?

Anyone want to generate a patch for this?

Dan

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