Re: [Qemu-devel] [PATCH v12 04/17] hbitmap: add hbitmap_merge

[Max Reitz <mreitz@redhat.com>]

On 2015-02-09 at 20:35, 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 <jsnow@redhat.com>
> ---
>   include/qemu/hbitmap.h | 11 +++++++++++
>   util/hbitmap.c         | 32 ++++++++++++++++++++++++++++++++
>   2 files changed, 43 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>