The patch titled
Subject: bitmap: optimise bitmap_set and bitmap_clear of a single bit
has been added to the -mm tree. Its filename is
bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Subject: bitmap: optimise bitmap_set and bitmap_clear of a single bit
We have eight users calling bitmap_clear for a single bit and seventeen
calling bitmap_set for a single bit. Rather than fix all of them to call
__clear_bit or __set_bit, turn bitmap_clear and bitmap_set into inline
functions and make this special case efficient.
Link: http://lkml.kernel.org/r/20170628153221.11322-3-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitmap.h | 23 ++++++++++++++++++++---
lib/bitmap.c | 8 ++++----
lib/test_bitmap.c | 3 ---
3 files changed, 24 insertions(+), 10 deletions(-)
diff -puN include/linux/bitmap.h~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit include/linux/bitmap.h
--- a/include/linux/bitmap.h~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit
+++ a/include/linux/bitmap.h
@@ -112,9 +112,8 @@ extern int __bitmap_intersects(const uns
extern int __bitmap_subset(const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int nbits);
extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
-
-extern void bitmap_set(unsigned long *map, unsigned int start, int len);
-extern void bitmap_clear(unsigned long *map, unsigned int start, int len);
+extern void __bitmap_set(unsigned long *map, unsigned int start, int len);
+extern void __bitmap_clear(unsigned long *map, unsigned int start, int len);
extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long size,
@@ -315,6 +314,24 @@ static __always_inline int bitmap_weight
return __bitmap_weight(src, nbits);
}
+static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
+ unsigned int nbits)
+{
+ if (__builtin_constant_p(nbits) && nbits == 1)
+ __set_bit(start, map);
+ else
+ __bitmap_set(map, start, nbits);
+}
+
+static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
+ unsigned int nbits)
+{
+ if (__builtin_constant_p(nbits) && nbits == 1)
+ __clear_bit(start, map);
+ else
+ __bitmap_clear(map, start, nbits);
+}
+
static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
unsigned int shift, int nbits)
{
diff -puN lib/bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit lib/bitmap.c
--- a/lib/bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit
+++ a/lib/bitmap.c
@@ -251,7 +251,7 @@ int __bitmap_weight(const unsigned long
}
EXPORT_SYMBOL(__bitmap_weight);
-void bitmap_set(unsigned long *map, unsigned int start, int len)
+void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
unsigned long *p = map + BIT_WORD(start);
const unsigned int size = start + len;
@@ -270,9 +270,9 @@ void bitmap_set(unsigned long *map, unsi
*p |= mask_to_set;
}
}
-EXPORT_SYMBOL(bitmap_set);
+EXPORT_SYMBOL(__bitmap_set);
-void bitmap_clear(unsigned long *map, unsigned int start, int len)
+void __bitmap_clear(unsigned long *map, unsigned int start, int len)
{
unsigned long *p = map + BIT_WORD(start);
const unsigned int size = start + len;
@@ -291,7 +291,7 @@ void bitmap_clear(unsigned long *map, un
*p &= ~mask_to_clear;
}
}
-EXPORT_SYMBOL(bitmap_clear);
+EXPORT_SYMBOL(__bitmap_clear);
/**
* bitmap_find_next_zero_area_off - find a contiguous aligned zero area
diff -puN lib/test_bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit lib/test_bitmap.c
--- a/lib/test_bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit
+++ a/lib/test_bitmap.c
@@ -333,9 +333,6 @@ static void __init test_bitmap_u32_array
}
}
-#define __bitmap_set(a, b, c) bitmap_set(a, b, c)
-#define __bitmap_clear(a, b, c) bitmap_clear(a, b, c)
-
static void noinline __init test_mem_optimisations(void)
{
DECLARE_BITMAP(bmap1, 1024);
_
Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are
test_bitmap-add-optimisation-tests.patch
bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit.patch
turn-bitmap_set-and-bitmap_clear-into-memset-when-possible.patch
bitmap-use-memcmp-optimisation-in-more-situations.patch
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