[PATCH 0/3] Improve bitmap_empty and bitmap_full

[PATCH 0/3] Improve bitmap_empty and bitmap_full

[Jia He]

find_fisrt_{zero_}bit are too heavy for bitmap_{full,empty}. We don't 
need to calculate and compare the position of bitmap. This set of patch
instroduces lightweight api and replaces the heavy one.

Jia He (3):
  linux/bitmap: Move 2 mask macro from bitmap.h to bitops.h
  lib: Introduce 2 find bit api: all_is_bit_{one,zero}
  linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api 

 include/asm-generic/bitops/find.h |  3 +++
 include/linux/bitmap.h            |  7 ++----
 include/linux/bitops.h            |  4 ++++
 lib/find_bit.c                    | 50 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 59 insertions(+), 5 deletions(-)

-- 
2.5.0

[PATCH 1/3] linux/bitmap: Move 2 mask macro to bitops.h

[Jia He]

This patch moves the mask macro to bitops.h and then the new introduced
api in find_bit.c can use it.

Signed-off-by: Jia He <hejianet@gmail.com>
---
 include/linux/bitmap.h | 3 ---
 include/linux/bitops.h | 4 ++++
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 9653fdb..15524f6 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -172,9 +172,6 @@ extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int
 extern int bitmap_print_to_pagebuf(bool list, char *buf,
 				   const unsigned long *maskp, int nmaskbits);
 
-#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
-#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
-
 #define small_const_nbits(nbits) \
 	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG)
 
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 2b8ed12..b881028 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -24,6 +24,10 @@
 #define GENMASK_ULL(h, l) \
 	(((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
 
+/* For bitmap ops*/
+#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
+#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
+
 extern unsigned int __sw_hweight8(unsigned int w);
 extern unsigned int __sw_hweight16(unsigned int w);
 extern unsigned int __sw_hweight32(unsigned int w);
-- 
2.5.0

[PATCH 2/3] lib: Introduce 2 find bit api: all_is_bit_{one,zero}

[Jia He]

This patch introduces 2 lightweight bit api.
all_bit_is_zero return 1 if the bit string is all zero.
The addr is the start address, the size is the bit size of the bit string.
all_bit_is_one is the opposite.

Signed-off-by: Jia He <hejianet@gmail.com>
---
 lib/find_bit.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/lib/find_bit.c b/lib/find_bit.c
index 18072ea..1d56d8d 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
 EXPORT_SYMBOL(find_last_bit);
 #endif
 
+#ifndef all_bit_is_zero
+/*
+ * return val: 1 means all bit is zero
+ */
+unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size)
+{
+	unsigned long idx;
+	unsigned long mask = size;
+
+	if (unlikely(size == 0))
+		return 1;
+
+	if (size > BITS_PER_LONG) {
+		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
+			if (addr[idx])
+				return 0;
+
+		mask = size - (idx - 1) * BITS_PER_LONG;
+	}
+
+	return !(*addr & BITMAP_LAST_WORD_MASK(mask));
+}
+EXPORT_SYMBOL(all_bit_is_zero);
+#endif
+
+#ifndef all_bit_is_one
+/*
+ * return val: 1 means all bit is one
+ */
+unsigned int all_bit_is_one(const unsigned long *addr, unsigned size)
+{
+	unsigned long idx;
+	unsigned long mask = size;
+
+	if (unlikely(size == 0))
+		return 1;
+
+	if (size > BITS_PER_LONG) {
+		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
+			if (~addr[idx])
+				return 0;
+
+		mask = size - (idx - 1) * BITS_PER_LONG;
+	}
+
+	return !(~(*addr) & BITMAP_LAST_WORD_MASK(mask));
+}
+EXPORT_SYMBOL(all_bit_is_one);
+#endif
+
 #ifdef __BIG_ENDIAN
 
 /* include/linux/byteorder does not support "unsigned long" type */
-- 
2.5.0

[PATCH 3/3] linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api

[Jia He]

This is to replace find_fisrt_{zero_}bit with the new lightweight api 
all_bit_is_{one,zero} in bitmap_{full,empty}

Signed-off-by: Jia He <hejianet@gmail.com>
---
 include/asm-generic/bitops/find.h | 3 +++
 include/linux/bitmap.h            | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 998d4d5..1ec1d45 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -59,4 +59,7 @@ extern unsigned long find_first_zero_bit(const unsigned long *addr,
 
 #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
 
+extern unsigned int all_bit_is_one(const unsigned long *addr, unsigned size);
+extern unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size);
+
 #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 15524f6..8877a68 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -281,7 +281,7 @@ static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
 	if (small_const_nbits(nbits))
 		return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
 
-	return find_first_bit(src, nbits) == nbits;
+	return all_bit_is_zero(src, nbits);
 }
 
 static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
@@ -289,7 +289,7 @@ static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
 	if (small_const_nbits(nbits))
 		return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
 
-	return find_first_zero_bit(src, nbits) == nbits;
+	return all_bit_is_one(src, nbits);
 }
 
 static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
-- 
2.5.0

Re: [PATCH 3/3] linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 3177 bytes --]

Hi Jia,

[auto build test ERROR on: v4.4-rc1]
[also build test ERROR on: next-20151118]

url:    https://github.com/0day-ci/linux/commits/Jia-He/Improve-bitmap_empty-and-bitmap_full/20151119-103554
config: m68k-allyesconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m68k 

All errors (new ones prefixed by >>):

   kernel/time/Kconfig:155:warning: range is invalid
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   In file included from include/linux/cpumask.h:11:0,
                    from include/linux/rcupdate.h:40,
                    from include/linux/rbtree.h:34,
                    from include/linux/sched.h:22,
                    from arch/m68k/kernel/asm-offsets.c:14:
   include/linux/bitmap.h: In function 'bitmap_empty':
>> include/linux/bitmap.h:284:2: error: implicit declaration of function 'all_bit_is_zero' [-Werror=implicit-function-declaration]
     return all_bit_is_zero(src, nbits);
     ^
   include/linux/bitmap.h: In function 'bitmap_full':
>> include/linux/bitmap.h:292:2: error: implicit declaration of function 'all_bit_is_one' [-Werror=implicit-function-declaration]
     return all_bit_is_one(src, nbits);
     ^
   cc1: some warnings being treated as errors
   make[2]: *** [arch/m68k/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2

vim +/all_bit_is_zero +284 include/linux/bitmap.h

   278	
   279	static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
   280	{
   281		if (small_const_nbits(nbits))
   282			return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
   283	
 > 284		return all_bit_is_zero(src, nbits);
   285	}
   286	
   287	static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
   288	{
   289		if (small_const_nbits(nbits))
   290			return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
   291	
 > 292		return all_bit_is_one(src, nbits);
   293	}
   294	
   295	static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
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Re: [PATCH 3/3] linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 3177 bytes --]

Hi Jia,

[auto build test ERROR on: v4.4-rc1]
[also build test ERROR on: next-20151118]

url:    https://github.com/0day-ci/linux/commits/Jia-He/Improve-bitmap_empty-and-bitmap_full/20151119-103554
config: m68k-allyesconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m68k 

All errors (new ones prefixed by >>):

   kernel/time/Kconfig:155:warning: range is invalid
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   In file included from include/linux/cpumask.h:11:0,
                    from include/linux/rcupdate.h:40,
                    from include/linux/rbtree.h:34,
                    from include/linux/sched.h:22,
                    from arch/m68k/kernel/asm-offsets.c:14:
   include/linux/bitmap.h: In function 'bitmap_empty':
>> include/linux/bitmap.h:284:2: error: implicit declaration of function 'all_bit_is_zero' [-Werror=implicit-function-declaration]
     return all_bit_is_zero(src, nbits);
     ^
   include/linux/bitmap.h: In function 'bitmap_full':
>> include/linux/bitmap.h:292:2: error: implicit declaration of function 'all_bit_is_one' [-Werror=implicit-function-declaration]
     return all_bit_is_one(src, nbits);
     ^
   cc1: some warnings being treated as errors
   make[2]: *** [arch/m68k/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2

vim +/all_bit_is_zero +284 include/linux/bitmap.h

   278	
   279	static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
   280	{
   281		if (small_const_nbits(nbits))
   282			return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
   283	
 > 284		return all_bit_is_zero(src, nbits);
   285	}
   286	
   287	static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
   288	{
   289		if (small_const_nbits(nbits))
   290			return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
   291	
 > 292		return all_bit_is_one(src, nbits);
   293	}
   294	
   295	static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
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Re: [PATCH 3/3] linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 3177 bytes --]

Hi Jia,

[auto build test ERROR on: v4.4-rc1]
[also build test ERROR on: next-20151118]

url:    https://github.com/0day-ci/linux/commits/Jia-He/Improve-bitmap_empty-and-bitmap_full/20151119-103554
config: m68k-allyesconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m68k 

All errors (new ones prefixed by >>):

   kernel/time/Kconfig:155:warning: range is invalid
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
   warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
   warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
   In file included from include/linux/cpumask.h:11:0,
                    from include/linux/rcupdate.h:40,
                    from include/linux/rbtree.h:34,
                    from include/linux/sched.h:22,
                    from arch/m68k/kernel/asm-offsets.c:14:
   include/linux/bitmap.h: In function 'bitmap_empty':
>> include/linux/bitmap.h:284:2: error: implicit declaration of function 'all_bit_is_zero' [-Werror=implicit-function-declaration]
     return all_bit_is_zero(src, nbits);
     ^
   include/linux/bitmap.h: In function 'bitmap_full':
>> include/linux/bitmap.h:292:2: error: implicit declaration of function 'all_bit_is_one' [-Werror=implicit-function-declaration]
     return all_bit_is_one(src, nbits);
     ^
   cc1: some warnings being treated as errors
   make[2]: *** [arch/m68k/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2

vim +/all_bit_is_zero +284 include/linux/bitmap.h

   278	
   279	static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
   280	{
   281		if (small_const_nbits(nbits))
   282			return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
   283	
 > 284		return all_bit_is_zero(src, nbits);
   285	}
   286	
   287	static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
   288	{
   289		if (small_const_nbits(nbits))
   290			return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
   291	
 > 292		return all_bit_is_one(src, nbits);
   293	}
   294	
   295	static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 35275 bytes --]

Re: [PATCH 3/3] linux/bitmap: Replace find_fisrt_{zero_}bit with the new lightweight api

[hejianet]

Thanks, I only compiled and tested in x86_64, will check what's wrong in 
m68k

B.R.
Justin


在 11/19/15 10:53 AM, kbuild test robot 写道:
> Hi Jia,
>
> [auto build test ERROR on: v4.4-rc1]
> [also build test ERROR on: next-20151118]
>
> url:    https://github.com/0day-ci/linux/commits/Jia-He/Improve-bitmap_empty-and-bitmap_full/20151119-103554
> config: m68k-allyesconfig (attached as .config)
> reproduce:
>          wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
>          chmod +x ~/bin/make.cross
>          # save the attached .config to linux build tree
>          make.cross ARCH=m68k
>
> All errors (new ones prefixed by >>):
>
>     kernel/time/Kconfig:155:warning: range is invalid
>     warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
>     warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
>     warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
>     warning: (USB_OTG_FSM && FSL_USB2_OTG && USB_MV_OTG) selects USB_OTG which has unmet direct dependencies (USB_SUPPORT && USB && PM)
>     warning: (SINGLE_MEMORY_CHUNK) selects NEED_MULTIPLE_NODES which has unmet direct dependencies (DISCONTIGMEM || NUMA)
>     warning: (PREEMPT && DEBUG_ATOMIC_SLEEP) selects PREEMPT_COUNT which has unmet direct dependencies (COLDFIRE)
>     In file included from include/linux/cpumask.h:11:0,
>                      from include/linux/rcupdate.h:40,
>                      from include/linux/rbtree.h:34,
>                      from include/linux/sched.h:22,
>                      from arch/m68k/kernel/asm-offsets.c:14:
>     include/linux/bitmap.h: In function 'bitmap_empty':
>>> include/linux/bitmap.h:284:2: error: implicit declaration of function 'all_bit_is_zero' [-Werror=implicit-function-declaration]
>       return all_bit_is_zero(src, nbits);
>       ^
>     include/linux/bitmap.h: In function 'bitmap_full':
>>> include/linux/bitmap.h:292:2: error: implicit declaration of function 'all_bit_is_one' [-Werror=implicit-function-declaration]
>       return all_bit_is_one(src, nbits);
>       ^
>     cc1: some warnings being treated as errors
>     make[2]: *** [arch/m68k/kernel/asm-offsets.s] Error 1
>     make[2]: Target '__build' not remade because of errors.
>     make[1]: *** [prepare0] Error 2
>     make[1]: Target 'prepare' not remade because of errors.
>     make: *** [sub-make] Error 2
>
> vim +/all_bit_is_zero +284 include/linux/bitmap.h
>
>     278	
>     279	static inline int bitmap_empty(const unsigned long *src, unsigned nbits)
>     280	{
>     281		if (small_const_nbits(nbits))
>     282			return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
>     283	
>   > 284		return all_bit_is_zero(src, nbits);
>     285	}
>     286	
>     287	static inline int bitmap_full(const unsigned long *src, unsigned int nbits)
>     288	{
>     289		if (small_const_nbits(nbits))
>     290			return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
>     291	
>   > 292		return all_bit_is_one(src, nbits);
>     293	}
>     294	
>     295	static __always_inline int bitmap_weight(const unsigned long *src, unsigned int nbits)
>
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCH 2/3] lib: Introduce 2 find bit api: all_is_bit_{one,zero}

[Geert Uytterhoeven]

On Thu, Nov 19, 2015 at 3:31 AM, Jia He <hejianet@gmail.com> wrote:
> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
> @@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
>  EXPORT_SYMBOL(find_last_bit);
>  #endif
>
> +#ifndef all_bit_is_zero
> +/*
> + * return val: 1 means all bit is zero
> + */
> +unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size)
> +{
> +       unsigned long idx;
> +       unsigned long mask = size;
> +
> +       if (unlikely(size == 0))
> +               return 1;
> +
> +       if (size > BITS_PER_LONG) {
> +               for (idx = 0; idx * BITS_PER_LONG < size; idx++)

Please move the multiplication (yes, a shift) out of the loop. Not all CPUs
have barrel shifters.

> +                       if (addr[idx])
> +                               return 0;
> +
> +               mask = size - (idx - 1) * BITS_PER_LONG;
> +       }
> +
> +       return !(*addr & BITMAP_LAST_WORD_MASK(mask));
> +}
> +EXPORT_SYMBOL(all_bit_is_zero);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 2/3] lib: Introduce 2 find bit api: all_is_bit_{one,zero}

[Michal Nazarewicz]

On Thu, Nov 19 2015, Jia He wrote:
> This patch introduces 2 lightweight bit api.
> all_bit_is_zero return 1 if the bit string is all zero.
> The addr is the start address, the size is the bit size of the bit string.
> all_bit_is_one is the opposite.
>
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
>  lib/find_bit.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/lib/find_bit.c b/lib/find_bit.c
> index 18072ea..1d56d8d 100644
> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
> @@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
>  EXPORT_SYMBOL(find_last_bit);
>  #endif
>  
> +#ifndef all_bit_is_zero
> +/*
> + * return val: 1 means all bit is zero
> + */
> +unsigned int all_bit_is_zero(const unsigned long *addr, unsigned
> size)

Why does it return unsigned int, not bool?

> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;

Uh?

> +	}
> +
> +	return !(*addr & BITMAP_LAST_WORD_MASK(mask));

BITMAP_LAST_WORD_MASK takes size not mask.

> +}

The whole implementation seems weird, this seems much better to me:

unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size)
{
	for (; size > BITS_PER_LONG; size -= BITS_PER_LONG, ++addr)
		if (*addr)
			return 0;
	return !size || !(*addr & BITMAP_LAST_WORD_MASK(size));
}

But to be honest I’m not entirely sure this is worth the effort.
find_next_bit and find_next_zero_bit may do a little bit more work but
some architectures have specialised optimised versions which will be
lost if all_bit_is_zero and all_bit_is_one are introduced.

> +EXPORT_SYMBOL(all_bit_is_zero);
> +#endif
> +
> +#ifndef all_bit_is_one
> +/*
> + * return val: 1 means all bit is one
> + */
> +unsigned int all_bit_is_one(const unsigned long *addr, unsigned size)
> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (~addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;
> +	}
> +
> +	return !(~(*addr) & BITMAP_LAST_WORD_MASK(mask));
> +}
> +EXPORT_SYMBOL(all_bit_is_one);
> +#endif
> +
>  #ifdef __BIG_ENDIAN
>  
>  /* include/linux/byteorder does not support "unsigned long" type */
> -- 
> 2.5.0
>

-- 
Best regards,                                            _     _
.o. | Liege of Serenely Enlightened Majesty of         o' \,=./ `o
..o | Computer Science,  ミハウ “mina86” ナザレヴイツ  (o o)
ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>-----ooO--(_)--Ooo--

Re: [PATCH 2/3] lib: Introduce 2 find bit api: all_is_bit_{one,zero}

[Michal Nazarewicz]

On Thu, Nov 19 2015, Jia He wrote:
> This patch introduces 2 lightweight bit api.
> all_bit_is_zero return 1 if the bit string is all zero.
> The addr is the start address, the size is the bit size of the bit string.
> all_bit_is_one is the opposite.
>
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
>  lib/find_bit.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/lib/find_bit.c b/lib/find_bit.c
> index 18072ea..1d56d8d 100644
> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
> @@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
>  EXPORT_SYMBOL(find_last_bit);
>  #endif
>  
> +#ifndef all_bit_is_zero
> +/*
> + * return val: 1 means all bit is zero
> + */
> +unsigned int all_bit_is_zero(const unsigned long *addr, unsigned
> size)

Why does it return unsigned int, not bool?

> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;

Uh?

> +	}
> +
> +	return !(*addr & BITMAP_LAST_WORD_MASK(mask));

BITMAP_LAST_WORD_MASK takes size not mask.

> +}

The whole implementation seems weird, this seems much better to me:

unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size)
{
	for (; size > BITS_PER_LONG; size -= BITS_PER_LONG, ++addr)
		if (*addr)
			return 0;
	return !size || !(*addr & BITMAP_LAST_WORD_MASK(size));
}

But to be honest I’m not entirely sure this is worth the effort.
find_next_bit and find_next_zero_bit may do a little bit more work but
some architectures have specialised optimised versions which will be
lost if all_bit_is_zero and all_bit_is_one are introduced.

> +EXPORT_SYMBOL(all_bit_is_zero);
> +#endif
> +
> +#ifndef all_bit_is_one
> +/*
> + * return val: 1 means all bit is one
> + */
> +unsigned int all_bit_is_one(const unsigned long *addr, unsigned size)
> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (~addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;
> +	}
> +
> +	return !(~(*addr) & BITMAP_LAST_WORD_MASK(mask));
> +}
> +EXPORT_SYMBOL(all_bit_is_one);
> +#endif
> +
>  #ifdef __BIG_ENDIAN
>  
>  /* include/linux/byteorder does not support "unsigned long" type */
> -- 
> 2.5.0
>

-- 
Best regards,                                            _     _
.o. | Liege of Serenely Enlightened Majesty of         o' \,=./ `o
..o | Computer Science,  ミハウ “mina86” ナザレヴイツ  (o o)
ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>-----ooO--(_)--Ooo--

Re: [PATCH 2/3] lib: Introduce 2 find bit api: all_is_bit_{one,zero}

[Michal Nazarewicz]

On Thu, Nov 19 2015, Jia He wrote:
> This patch introduces 2 lightweight bit api.
> all_bit_is_zero return 1 if the bit string is all zero.
> The addr is the start address, the size is the bit size of the bit string.
> all_bit_is_one is the opposite.
>
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
>  lib/find_bit.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/lib/find_bit.c b/lib/find_bit.c
> index 18072ea..1d56d8d 100644
> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
> @@ -131,6 +131,56 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
>  EXPORT_SYMBOL(find_last_bit);
>  #endif
>  
> +#ifndef all_bit_is_zero
> +/*
> + * return val: 1 means all bit is zero
> + */
> +unsigned int all_bit_is_zero(const unsigned long *addr, unsigned
> size)

Why does it return unsigned int, not bool?

> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;

Uh?

> +	}
> +
> +	return !(*addr & BITMAP_LAST_WORD_MASK(mask));

BITMAP_LAST_WORD_MASK takes size not mask.

> +}

The whole implementation seems weird, this seems much better to me:

unsigned int all_bit_is_zero(const unsigned long *addr, unsigned size)
{
	for (; size > BITS_PER_LONG; size -= BITS_PER_LONG, ++addr)
		if (*addr)
			return 0;
	return !size || !(*addr & BITMAP_LAST_WORD_MASK(size));
}

But to be honest I’m not entirely sure this is worth the effort.
find_next_bit and find_next_zero_bit may do a little bit more work but
some architectures have specialised optimised versions which will be
lost if all_bit_is_zero and all_bit_is_one are introduced.

> +EXPORT_SYMBOL(all_bit_is_zero);
> +#endif
> +
> +#ifndef all_bit_is_one
> +/*
> + * return val: 1 means all bit is one
> + */
> +unsigned int all_bit_is_one(const unsigned long *addr, unsigned size)
> +{
> +	unsigned long idx;
> +	unsigned long mask = size;
> +
> +	if (unlikely(size == 0))
> +		return 1;
> +
> +	if (size > BITS_PER_LONG) {
> +		for (idx = 0; idx * BITS_PER_LONG < size; idx++)
> +			if (~addr[idx])
> +				return 0;
> +
> +		mask = size - (idx - 1) * BITS_PER_LONG;
> +	}
> +
> +	return !(~(*addr) & BITMAP_LAST_WORD_MASK(mask));
> +}
> +EXPORT_SYMBOL(all_bit_is_one);
> +#endif
> +
>  #ifdef __BIG_ENDIAN
>  
>  /* include/linux/byteorder does not support "unsigned long" type */
> -- 
> 2.5.0
>

-- 
Best regards,                                            _     _
.o. | Liege of Serenely Enlightened Majesty of         o' \,=./ `o
..o | Computer Science,  ミハウ “mina86” ナザレヴイツ  (o o)
ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>-----ooO--(_)--Ooo--

Re: [PATCH 1/3] linux/bitmap: Move 2 mask macro to bitops.h

[Andy Shevchenko]

On Thu, Nov 19, 2015 at 4:31 AM, Jia He <hejianet@gmail.com> wrote:
> This patch moves the mask macro to bitops.h and then the new introduced
> api in find_bit.c can use it.

Why API can't use GENMASK() instead?

>
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
>  include/linux/bitmap.h | 3 ---
>  include/linux/bitops.h | 4 ++++
>  2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index 9653fdb..15524f6 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -172,9 +172,6 @@ extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int
>  extern int bitmap_print_to_pagebuf(bool list, char *buf,
>                                    const unsigned long *maskp, int nmaskbits);
>
> -#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
> -#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
> -
>  #define small_const_nbits(nbits) \
>         (__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG)
>
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 2b8ed12..b881028 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -24,6 +24,10 @@
>  #define GENMASK_ULL(h, l) \
>         (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
>
> +/* For bitmap ops*/
> +#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
> +#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
> +
>  extern unsigned int __sw_hweight8(unsigned int w);
>  extern unsigned int __sw_hweight16(unsigned int w);
>  extern unsigned int __sw_hweight32(unsigned int w);
> --
> 2.5.0
>
> --
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-- 
With Best Regards,
Andy Shevchenko