[Xen-devel] One question on alloc_bitmap

Jiang, Yunhong
Thu, 18 Sep 2008 15:16:02 -0000

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?

Thanks