Am 18.11.2013 17:27, schrieb Anthony Liguori:

On Nov 18, 2013 12:20 AM, "Peter Lieven" <pl@kamp.de> wrote:
>
> vnc_update_client currently scans the dirty bitmap of each client
> bitwise which is a very costly operation if only few bits are dirty.
> vnc_refresh_server_surface does almost the same.
> this patch optimizes both by utilizing the heavily optimized
> function find_next_bit to find the offset of the next dirty
> bit in the dirty bitmaps.
>
> Signed-off-by: Peter Lieven <pl@kamp.de>

Can you include performance data?

I hoped that the checking 32bits (pipelined) at once compared to
checking 32bits one-by-one would be convincing enough ;-)

Do you have a special test in mind? Otherwise I could try
to create an artificial test case with e.g. no bits dirty, all bits
dirty, only a few bits dirty (cursor update) and compare the
timing for both versions.

Peter