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Re: [Xen-devel] [PATCH 2/6] xen: Add NUMA support to Xen

On 2 May 2006, at 15:53, Ryan Harper wrote:

Loops over every memory chunk structure on the alloc/free paths aren't
going to get merged. There's no need for it -- in most cases memory
chunks are probably aligned on a MAX_ORDER boundary (or they will be
when I reduce MAX_ORDER, which requires me to fix up our Linux swiotlb
a bit first). When that isn't the case you can simply reserve guard
pages at the start and end of such chunks to avoid cross-chunk merging.

I'll toss page_spans_chunk() and the user in the free path, use some
guard pages and resubmit.

Great. Please do make it conditional on the start/end not being on a MAX_ORDER boundary though -- that's a worthwhile optimisation to avoid the guard page.

  page_to_node still uses the chunk array to
determine which node a struct page_info belongs to, which is used in the
free path.  Is that acceptable?

It'll have to do for now. As long as it doesn't suck on small NUMA or non NUMA systems we can improve it later (extra flags in each page structure, or some faster lookup structure).

 -- Keir

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