On Wed, Sep 24, 2014 at 11:24:02AM -0700, Jarno Rajahalme wrote:
> Before:
>
> $ tests/ovstest test-bitmap benchmark 1000000
> bitmap equal: 328 ms
> bitmap scan: 8159 ms
>
> After:
>
> $ tests/ovstest test-bitmap benchmark 1000000
> bitmap equal: 230 ms
> bitmap scan: 185 ms
>
> Signed-off-by: Kmindg <kmi...@gmail.com>
> Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
Very nice.
In bitmap_equal(), I think that this:
i = ROUND_DOWN(n, BITMAP_ULONG_BITS);
n -= i; /* Remaining bits. */
can just be written "n %= BITMAP_ULONG_BITS;"
Did you consider writing a single bitmap scan function that takes a
parameter to XOR with the bitmap words? Then bitmap_scan1() would
pass 0 and bitmap_scan0() would pass ULONG_MAX. If this bitmap scan
function were marked ALWAYS_INLINE (and the compiler honored it) then
it would eliminate some redundant code.
In bitmap_scan[01], the inner "if (!unit)" seems to not be needed,
because the outer start < end check will also do the right thing. I
don't know whether it is better from a performance standpoint to
remove the inner check, or whether it is better from an "obviously
correct" standpoint to keep it.
The comment on bitmap_init1() about its return value is wrong.
Acked-by: Ben Pfaff <b...@nicira.com>
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