On Sun, Nov 28, 2021 at 05:37:19AM +0100, Michał Mirosław wrote:

On Sat, Nov 27, 2021 at 07:56:57PM -0800, Yury Norov wrote:

quoted

Now as we have bitmap_weight_eq(), switch bitmap_full() and
bitmap_empty() to using it.

[...]

quoted

-static inline bool bitmap_empty(const unsigned long *src, unsigned nbits)
-{
-	if (small_const_nbits(nbits))
-		return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
-
-	return find_first_bit(src, nbits) == nbits;
-}

[...]

quoted

+static __always_inline bool bitmap_empty(const unsigned long *src, unsigned int nbits)
+{
+	return bitmap_weight_eq(src, nbits, 0);
+}

[..]

What's the speed difference? Have you benchmarked this?

bitmap_weight_eq() should be faster than find_first_bit(), but the
difference is few cycles, so I didn't bother measuring it.

New version looks just better.