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linux/include/asm-generic/bitops/find.h

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[PATCH] bitops: generic find_{next,first}{,_zero}_bit() This patch introduces the C-language equivalents of the functions below: unsigned logn find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size); unsigned long find_first_bit(const unsigned long *addr, unsigned long size); In include/asm-generic/bitops/find.h This code largely copied from: arch/powerpc/lib/bitops.c Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 02:39:11 -07:00
#ifndef _ASM_GENERIC_BITOPS_FIND_H_
#define _ASM_GENERIC_BITOPS_FIND_H_
x86, generic: optimize find_next_(zero_)bit for small constant-size bitmaps This moves an optimization for searching constant-sized small bitmaps form x86_64-specific to generic code. On an i386 defconfig (the x86#testing one), the size of vmlinux hardly changes with this applied. I have observed only four places where this optimization avoids a call into find_next_bit: In the functions return_unused_surplus_pages, alloc_fresh_huge_page, and adjust_pool_surplus, this patch avoids a call for a 1-bit bitmap. In __next_cpu a call is avoided for a 32-bit bitmap. That's it. On x86_64, 52 locations are optimized with a minimal increase in code size: Current #testing defconfig: 146 x bsf, 27 x find_next_*bit text data bss dec hex filename 5392637 846592 724424 6963653 6a41c5 vmlinux After removing the x86_64 specific optimization for find_next_*bit: 94 x bsf, 79 x find_next_*bit text data bss dec hex filename 5392358 846592 724424 6963374 6a40ae vmlinux After this patch (making the optimization generic): 146 x bsf, 27 x find_next_*bit text data bss dec hex filename 5392396 846592 724424 6963412 6a40d4 vmlinux [ tglx@linutronix.de: build fixes ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-11 08:17:19 -07:00
#ifndef CONFIG_GENERIC_FIND_NEXT_BIT
[PATCH] bitops: generic find_{next,first}{,_zero}_bit() This patch introduces the C-language equivalents of the functions below: unsigned logn find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size); unsigned long find_first_bit(const unsigned long *addr, unsigned long size); In include/asm-generic/bitops/find.h This code largely copied from: arch/powerpc/lib/bitops.c Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 02:39:11 -07:00
extern unsigned long find_next_bit(const unsigned long *addr, unsigned long
size, unsigned long offset);
extern unsigned long find_next_zero_bit(const unsigned long *addr, unsigned
long size, unsigned long offset);
x86, generic: optimize find_next_(zero_)bit for small constant-size bitmaps This moves an optimization for searching constant-sized small bitmaps form x86_64-specific to generic code. On an i386 defconfig (the x86#testing one), the size of vmlinux hardly changes with this applied. I have observed only four places where this optimization avoids a call into find_next_bit: In the functions return_unused_surplus_pages, alloc_fresh_huge_page, and adjust_pool_surplus, this patch avoids a call for a 1-bit bitmap. In __next_cpu a call is avoided for a 32-bit bitmap. That's it. On x86_64, 52 locations are optimized with a minimal increase in code size: Current #testing defconfig: 146 x bsf, 27 x find_next_*bit text data bss dec hex filename 5392637 846592 724424 6963653 6a41c5 vmlinux After removing the x86_64 specific optimization for find_next_*bit: 94 x bsf, 79 x find_next_*bit text data bss dec hex filename 5392358 846592 724424 6963374 6a40ae vmlinux After this patch (making the optimization generic): 146 x bsf, 27 x find_next_*bit text data bss dec hex filename 5392396 846592 724424 6963412 6a40d4 vmlinux [ tglx@linutronix.de: build fixes ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-11 08:17:19 -07:00
#endif
[PATCH] bitops: generic find_{next,first}{,_zero}_bit() This patch introduces the C-language equivalents of the functions below: unsigned logn find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, unsigned long offset); unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size); unsigned long find_first_bit(const unsigned long *addr, unsigned long size); In include/asm-generic/bitops/find.h This code largely copied from: arch/powerpc/lib/bitops.c Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 02:39:11 -07:00
#define find_first_bit(addr, size) find_next_bit((addr), (size), 0)
#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
#endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
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