Re: [Qemu-devel] [PATCH v6 07/21] hbitmap: add hbitmap_merge

[Stefan Hajnoczi]

On Fri, Apr 17, 2015 at 07:49:55PM -0400, John Snow wrote:
> We add a bitmap merge operation to assist in error cases
> where we wish to combine two bitmaps together.
> 
> This is algorithmically O(bits) provided HBITMAP_LEVELS remains
> constant. For a full bitmap on a 64bit machine:
> sum(bits/64^k, k, 0, HBITMAP_LEVELS) ~= 1.01587 * bits
> 
> We may be able to improve running speed for particularly sparse
> bitmaps by using iterators, but the running time for dense maps
> will be worse.
> 
> We present the simpler solution first, and we can refine it later
> if needed.
> 
> Signed-off-by: John Snow <address@hidden>
> ---
>  include/qemu/hbitmap.h | 13 +++++++++++++
>  util/hbitmap.c         | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)

Reviewed-by: Stefan Hajnoczi <address@hidden>

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