[PATCH] lib: Make _find_next_bit helper function inline

[Cassidy Burden]

I've tested Yury Norov's find_bit reimplementation with the test_find_bit
module (https://lkml.org/lkml/2015/3/8/141) and measured about 35-40%
performance degradation on arm64 3.18 run with fixed CPU frequency.

The performance degradation appears to be caused by the
helper function _find_next_bit. After inlining this function into
find_next_bit and find_next_zero_bit I get slightly better performance
than the old implementation:

find_next_zero_bit          find_next_bit
old      new     inline     old      new     inline
26       36      24         24       33      23
25       36      24         24       33      23
26       36      24         24       33      23
25       36      24         24       33      23
25       36      24         24       33      23
25       37      24         24       33      23
25       37      24         24       33      23
25       37      24         24       33      23
25       36      24         24       33      23
25       37      24         24       33      23

Signed-off-by: Cassidy Burden <cburden at codeaurora.org>
Cc: Alexey Klimov <klimov.linux at gmail.com>
Cc: David S. Miller <davem at davemloft.net>
Cc: Daniel Borkmann <dborkman at redhat.com>
Cc: Hannes Frederic Sowa <hannes at stressinduktion.org>
Cc: Lai Jiangshan <laijs at cn.fujitsu.com>
Cc: Mark Salter <msalter at redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi at linaro.org>
Cc: Thomas Graf <tgraf at suug.ch>
Cc: Valentin Rothberg <valentinrothberg at gmail.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 lib/find_bit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/find_bit.c b/lib/find_bit.c
index 18072ea..d0e04f9 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -28,7 +28,7 @@
  * find_next_zero_bit.  The difference is the "invert" argument, which
  * is XORed with each fetched word before searching it for one bits.
  */
-static unsigned long _find_next_bit(const unsigned long *addr,
+static inline unsigned long _find_next_bit(const unsigned long *addr,
 		unsigned long nbits, unsigned long start, unsigned long invert)
 {
 	unsigned long tmp;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project