* + lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch added to -mm tree
@ 2021-04-01 0:54 akpm
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From: akpm @ 2021-04-01 0:54 UTC (permalink / raw)
To: aklimov, andriy.shevchenko, arnd, dalias, dennis, dsterba, geert,
glaubitz, jianpeng.ma, joe, jpoimboe, linux, mm-commits,
richard.weiyang, sbrivio, wsa+renesas, ysato, yury.norov
The patch titled
Subject: lib: add fast path for find_first_*_bit() and find_last_bit()
has been added to the -mm tree. Its filename is
lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Yury Norov <yury.norov@gmail.com>
Subject: lib: add fast path for find_first_*_bit() and find_last_bit()
Similarly to bitmap functions, users would benefit if we'll handle a case
of small-size bitmaps that fit into a single word.
While here, move the find_last_bit() declaration to bitops/find.h where
other find_*_bit() functions sit.
Link: https://lkml.kernel.org/r/20210401003153.97325-11-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Alexey Klimov <aklimov@redhat.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jianpeng Ma <jianpeng.ma@intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Stefano Brivio <sbrivio@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/asm-generic/bitops/find.h | 50 +++++++++++++++++++++++++---
include/linux/bitops.h | 12 ------
lib/find_bit.c | 12 +++---
3 files changed, 52 insertions(+), 22 deletions(-)
--- a/include/asm-generic/bitops/find.h~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/include/asm-generic/bitops/find.h
@@ -5,6 +5,9 @@
extern unsigned long _find_next_bit(const unsigned long *addr1,
const unsigned long *addr2, unsigned long nbits,
unsigned long start, unsigned long invert, unsigned long le);
+extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size);
#ifndef find_next_bit
/**
@@ -102,8 +105,17 @@ unsigned long find_next_zero_bit(const u
* Returns the bit number of the first set bit.
* If no bits are set, returns @size.
*/
-extern unsigned long find_first_bit(const unsigned long *addr,
- unsigned long size);
+static inline
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr & GENMASK(size - 1, 0);
+
+ return val ? __ffs(val) : size;
+ }
+
+ return _find_first_bit(addr, size);
+}
/**
* find_first_zero_bit - find the first cleared bit in a memory region
@@ -113,8 +125,17 @@ extern unsigned long find_first_bit(cons
* Returns the bit number of the first cleared bit.
* If no bits are zero, returns @size.
*/
-extern unsigned long find_first_zero_bit(const unsigned long *addr,
- unsigned long size);
+static inline
+unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr | ~GENMASK(size - 1, 0);
+
+ return val == ~0UL ? size : ffz(val);
+ }
+
+ return _find_first_zero_bit(addr, size);
+}
#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifndef find_first_bit
@@ -126,6 +147,27 @@ extern unsigned long find_first_zero_bit
#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
+#ifndef find_last_bit
+/**
+ * find_last_bit - find the last set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The number of bits to search
+ *
+ * Returns the bit number of the last set bit, or size.
+ */
+static inline
+unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr & GENMASK(size - 1, 0);
+
+ return val ? __fls(val) : size;
+ }
+
+ return _find_last_bit(addr, size);
+}
+#endif
+
/**
* find_next_clump8 - find next 8-bit clump with set bits in a memory region
* @clump: location to store copy of found clump
--- a/include/linux/bitops.h~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/include/linux/bitops.h
@@ -286,17 +286,5 @@ static __always_inline void __assign_bit
})
#endif
-#ifndef find_last_bit
-/**
- * find_last_bit - find the last set bit in a memory region
- * @addr: The address to start the search at
- * @size: The number of bits to search
- *
- * Returns the bit number of the last set bit, or size.
- */
-extern unsigned long find_last_bit(const unsigned long *addr,
- unsigned long size);
-#endif
-
#endif /* __KERNEL__ */
#endif
--- a/lib/find_bit.c~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/lib/find_bit.c
@@ -75,7 +75,7 @@ EXPORT_SYMBOL(_find_next_bit);
/*
* Find the first set bit in a memory region.
*/
-unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
{
unsigned long idx;
@@ -86,14 +86,14 @@ unsigned long find_first_bit(const unsig
return size;
}
-EXPORT_SYMBOL(find_first_bit);
+EXPORT_SYMBOL(_find_first_bit);
#endif
#ifndef find_first_zero_bit
/*
* Find the first cleared bit in a memory region.
*/
-unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
{
unsigned long idx;
@@ -104,11 +104,11 @@ unsigned long find_first_zero_bit(const
return size;
}
-EXPORT_SYMBOL(find_first_zero_bit);
+EXPORT_SYMBOL(_find_first_zero_bit);
#endif
#ifndef find_last_bit
-unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
{
if (size) {
unsigned long val = BITMAP_LAST_WORD_MASK(size);
@@ -124,7 +124,7 @@ unsigned long find_last_bit(const unsign
}
return size;
}
-EXPORT_SYMBOL(find_last_bit);
+EXPORT_SYMBOL(_find_last_bit);
#endif
unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
_
Patches currently in -mm which might be from yury.norov@gmail.com are
tools-disable-wno-type-limits.patch
tools-bitmap-sync-function-declarations-with-the-kernel.patch
tools-sync-bitmap_last_word_mask-macro-with-the-kernel.patch
arch-rearrange-headers-inclusion-order-in-asm-bitops-for-m68k-and-sh.patch
lib-extend-the-scope-of-small_const_nbits-macro.patch
tools-sync-small_const_nbits-macro-with-the-kernel.patch
lib-inline-_find_next_bit-wrappers.patch
tools-sync-find_next_bit-implementation.patch
lib-add-fast-path-for-find_next__bit.patch
lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch
tools-sync-lib-find_bit-implementation.patch
maintainers-add-entry-for-the-bitmap-api.patch
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2021-04-01 0:54 + lib-add-fast-path-for-find_first__bit-and-find_last_bit.patch added to -mm tree akpm
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