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Re: [XenPPC] [RFC] 64mb Chunk Allocator

On Thu, 2006-06-22 at 16:56 -0400, Michal Ostrowski wrote:
> How is this expected to be integrated into existing memory allocators in
> Xen?  Would the other allocators always allocate their own chunks to
> work with and divide them up into smaller pieces or would other
> allocators compete with the chunk allocator?

Yeah, I think this is the key question.

Once you've given a chunk to the heap allocator, I don't think you can
ever expect it to be defragmented and given back. I worry about the
classic fragmentation problem:
"Create domain." -> -ENOMEM
"How much memory is free?" -> lots and lots

> Whereas the allocation strategies chosen by Linux encourage
> fragmentation and make memory hot-unplug difficult, this could be an
> opportunity to introduce a generic large-granularity memory-management
> layer that makes it easier to deal with hot-plug and large pages.

That's an interesting point.

Hollis Blanchard
IBM Linux Technology Center

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