Commit ca1250bb authored Jun 07, 2018 by Yury Norov Committed by Linus Torvalds Jun 07, 2018

lib/bitmap.c: micro-optimization for __bitmap_complement()

Use BITS_TO_LONGS() macro to avoid calculation of reminder (bits %
BITS_PER_LONG) On ARM64 it saves 5 instruction for function - 16 before
and 11 after.

Link: http://lkml.kernel.org/r/20180411145914.6011-1-ynorov@caviumnetworks.com


Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 0455c747

lib/bitmap.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -64,12 +64,9 @@ EXPORT_SYMBOL(__bitmap_equal);

		void __bitmap_complement(unsigned long dst, const unsigned long src, unsigned int bits)
		{
		unsigned int k, lim = bits/BITS_PER_LONG;
		unsigned int k, lim = BITS_TO_LONGS(bits);
		for (k = 0; k < lim; ++k)
		dst[k] = ~src[k];

		if (bits % BITS_PER_LONG)
		dst[k] = ~src[k];
		}
		EXPORT_SYMBOL(__bitmap_complement);

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