[PATCH v3 00/14] lib/find_bit: fast path for small bitmaps

Yury Norov
2021-02-18T04:06:55Z

Bitmap operations are much simpler and faster in case of small bitmaps
which fit into a single word. In linux/bitmap.c we have a machinery that
allows compiler to replace actual function call with a few instructions
if bitmaps passed into the function are small and their size is known at
compile time.

find_*_bit() API lacks this functionality; but users will benefit from it
a lot. One important example is cpumask subsystem when
NR_CPUS <= BITS_PER_LONG.

Tools is synchronized with new implementation where needed.

v1: https://www.spinics.net/lists/kernel/msg3804727.html
v2: https://www.spinics.net/lists/linux-m68k/msg16945.html
v3: - split kernel and tools code;
- add FAST_PATH config option;
- add BITMAP API section to MAINTAINERS.

Yury Norov (14):
tools: disable -Wno-type-limits
tools: bitmap: sync function declarations with the kernel
arch: rearrange headers inclusion order in asm/bitops for m68k and sh
lib: introduce BITS_{FIRST,LAST} macro
tools: sync BITS_MASK macros with the kernel
bitsperlong.h: introduce SMALL_CONST() macro
tools: introduce SMALL_CONST() macro
lib/Kconfig: introduce FAST_PATH option
lib: inline _find_next_bit() wrappers
tools: sync find_next_bit implementation
lib: add fast path for find_next_*_bit()
lib: add fast path for find_first_*_bit() and find_last_bit()
tools: sync lib/find_bit implementation
MAINTAINERS: Add entry for the bitmap API

MAINTAINERS | 14 +++
arch/m68k/include/asm/bitops.h | 4 +-
arch/sh/include/asm/bitops.h | 3 +-
include/asm-generic/bitops/find.h | 108 +++++++++++++++++++++---
include/asm-generic/bitops/le.h | 38 ++++++++-
include/asm-generic/bitsperlong.h | 6 ++
include/linux/bitmap.h | 60 ++++++-------
include/linux/bitops.h | 12 ---
include/linux/bits.h | 6 ++
include/linux/cpumask.h | 8 +-
include/linux/netdev_features.h | 2 +-
include/linux/nodemask.h | 2 +-
lib/Kconfig | 7 ++
lib/bitmap.c | 26 +++---
lib/find_bit.c | 72 +++-------------
lib/genalloc.c | 8 +-
tools/include/asm-generic/bitops/find.h | 85 +++++++++++++++++--
tools/include/asm-generic/bitsperlong.h | 2 +
tools/include/linux/bitmap.h | 47 ++++-------
tools/include/linux/bits.h | 6 ++
tools/lib/bitmap.c | 10 +--
tools/lib/find_bit.c | 56 +++++-------
tools/scripts/Makefile.include | 1 +
tools/testing/radix-tree/bitmap.c | 4 +-
24 files changed, 362 insertions(+), 225 deletions(-)

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2.25.1