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Re: [Xen-devel] One question on alloc_bitmap

To: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] One question on alloc_bitmap
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 18 Sep 2008 16:20:52 +0100
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Thread-topic: [Xen-devel] One question on alloc_bitmap
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On 18/9/08 16:16, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:

> I have a question to the alloc_bitmap. Currently it is allocated in
> init_page_allocator() and is continous physical memory mapped in direct map
> (1:1 map) range. Would it be possible to support un-continous like what's done
> for frame table?
> Several reason I can think out that can be improved is: a) if memory sparsed
> arranged, like large hole in the memory, it may cost some memory b) if we want
> to support memory hot add, we can't increase this bitmap. c) this map is not
> NUMA aware, I'm not sure if it has any performance impact, although it is not
> accessed frequently.
> Any idea on it?

Yes, it could be sparsely allocated in future. No reason why not.

 -- Keir

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