| Message ID | 20210316015424.1999082-12-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | lib/find_bit: fast path for small bitmaps | expand |
On Mon, Mar 15, 2021 at 06:54:22PM -0700, Yury Norov wrote: > 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. > > Signed-off-by: Yury Norov <yury.norov@gmail.com> > --- > include/asm-generic/bitops/find.h | 50 ++++++++++++++++++++++++++++--- > include/linux/bitops.h | 12 -------- > lib/find_bit.c | 12 ++++---- > 3 files changed, 52 insertions(+), 22 deletions(-) > > diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h > index 4148c74a1e4d..8d818b304869 100644 > --- a/include/asm-generic/bitops/find.h > +++ b/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 unsigned long *addr, unsigned long size, > * 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 & BITS_FIRST(size - 1); > + > + return val ? __ffs(val) : size; This patch results in: include/asm-generic/bitops/find.h: In function 'find_last_bit': include/asm-generic/bitops/find.h:164:16: error: implicit declaration of function '__fls'; did you mean '__ffs'? and: ./include/asm-generic/bitops/__fls.h: At top level: ./include/asm-generic/bitops/__fls.h:13:38: error: conflicting types for '__fls' when building scripts/mod/devicetable-offsets.o. Seen with h8300 builds. Guenter > + } > + > + 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(const unsigned long *addr, > * 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 | ~BITS_FIRST(size - 1); > + > + 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(const unsigned long *addr, > > #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 & BITS_FIRST(size - 1); > + > + 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 > diff --git a/include/linux/bitops.h b/include/linux/bitops.h > index a5a48303b0f1..26bf15e6cd35 100644 > --- a/include/linux/bitops.h > +++ b/include/linux/bitops.h > @@ -286,17 +286,5 @@ static __always_inline void __assign_bit(long nr, volatile unsigned long *addr, > }) > #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 > diff --git a/lib/find_bit.c b/lib/find_bit.c > index 2470ae390f3c..e2c301d28568 100644 > --- a/lib/find_bit.c > +++ b/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 unsigned long *addr, unsigned long size) > > 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 unsigned long *addr, unsigned long size) > > 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 = BITS_FIRST_MASK(size - 1); > @@ -124,7 +124,7 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size) > } > 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,
On Tue, Apr 06, 2021 at 09:03:27AM -0700, Guenter Roeck wrote: > On Mon, Mar 15, 2021 at 06:54:22PM -0700, Yury Norov wrote: > > 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. > > > > Signed-off-by: Yury Norov <yury.norov@gmail.com> > > --- > > include/asm-generic/bitops/find.h | 50 ++++++++++++++++++++++++++++--- > > include/linux/bitops.h | 12 -------- > > lib/find_bit.c | 12 ++++---- > > 3 files changed, 52 insertions(+), 22 deletions(-) > > > > diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h > > index 4148c74a1e4d..8d818b304869 100644 > > --- a/include/asm-generic/bitops/find.h > > +++ b/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 unsigned long *addr, unsigned long size, > > * 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 & BITS_FIRST(size - 1); > > + > > + return val ? __ffs(val) : size; > > This patch results in: > > include/asm-generic/bitops/find.h: In function 'find_last_bit': > include/asm-generic/bitops/find.h:164:16: error: implicit declaration of function '__fls'; did you mean '__ffs'? > > and: > > ./include/asm-generic/bitops/__fls.h: At top level: > ./include/asm-generic/bitops/__fls.h:13:38: error: conflicting types for '__fls' > > when building scripts/mod/devicetable-offsets.o. > > Seen with h8300 builds. > > Guenter The patch is here: https://lkml.org/lkml/2021/4/1/1184 Yury
diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h index 4148c74a1e4d..8d818b304869 100644 --- a/include/asm-generic/bitops/find.h +++ b/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 unsigned long *addr, unsigned long size, * 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 & BITS_FIRST(size - 1); + + 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(const unsigned long *addr, * 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 | ~BITS_FIRST(size - 1); + + 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(const unsigned long *addr, #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 & BITS_FIRST(size - 1); + + 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 diff --git a/include/linux/bitops.h b/include/linux/bitops.h index a5a48303b0f1..26bf15e6cd35 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -286,17 +286,5 @@ static __always_inline void __assign_bit(long nr, volatile unsigned long *addr, }) #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 diff --git a/lib/find_bit.c b/lib/find_bit.c index 2470ae390f3c..e2c301d28568 100644 --- a/lib/find_bit.c +++ b/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 unsigned long *addr, unsigned long size) 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 unsigned long *addr, unsigned long size) 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 = BITS_FIRST_MASK(size - 1); @@ -124,7 +124,7 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size) } 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,
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. Signed-off-by: Yury Norov <yury.norov@gmail.com> --- include/asm-generic/bitops/find.h | 50 ++++++++++++++++++++++++++++--- include/linux/bitops.h | 12 -------- lib/find_bit.c | 12 ++++---- 3 files changed, 52 insertions(+), 22 deletions(-)