Re: [Xen-ia64-devel] Re: [Xen-devel] [PATCH 0/5] dump-core take 2:

[Jes Sorensen <jes@xxxxxxx>]

>>>>> "Kevin" == Tian, Kevin <kevin.tian@xxxxxxxxx> writes:

Kevin> Yeah, memory map may be sparse on ia64, but, only at physical
Kevin> level.  You can always present a compact pseudo physical layout
Kevin> to a domain, despite of sparse or not in real physical.:-) BTW,
Kevin> is it possible to save memmap into xenstore, so that multiple
Kevin> user components can communicate such info directly without
Kevin> xen's intervention?

Providing a fake linear memory map like that is totally broken, it
means the domU operating system will not be able to benefit from NUMA
information and do appropriate scheduling. The domU pages needs to be
placed in the metaphysical memory zones that match their physical zone
to get this right.

We can provide a virtual linear map for special cases, like to support
lesser operating systems that can't handle real computers, but the
general case needs to be that pages go into the metaphysical zone that
matches their real physical zone.

This is applicable to any NUMA system, not just ia64 systems, so with
x86_64 becoming mainstream they will need it there too.

A linear scan of the pfn list is just wrong, one should never do that.

Cheers,
Jes

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