From 6fd92b63d0626a8fe7eb8e2e50d19ecaa18cb412 Mon Sep 17 00:00:00 2001 From: Alexander van Heukelum <heukelum@mailshack.com> Date: Sun, 9 Mar 2008 21:01:04 +0100 Subject: x86: change x86 to use generic find_next_bit The versions with inline assembly are in fact slower on the machines I tested them on (in userspace) (Athlon XP 2800+, p4-like Xeon 2.8GHz, AMD Opteron 270). The i386-version needed a fix similar to 06024f21 to avoid crashing the benchmark. Benchmark using: gcc -fomit-frame-pointer -Os. For each bitmap size 1...512, for each possible bitmap with one bit set, for each possible offset: find the position of the first bit starting at offset. If you follow ;). Times include setup of the bitmap and checking of the results. Athlon Xeon Opteron 32/64bit x86-specific: 0m3.692s 0m2.820s 0m3.196s / 0m2.480s generic: 0m2.622s 0m1.662s 0m2.100s / 0m1.572s If the bitmap size is not a multiple of BITS_PER_LONG, and no set (cleared) bit is found, find_next_bit (find_next_zero_bit) returns a value outside of the range [0, size]. The generic version always returns exactly size. The generic version also uses unsigned long everywhere, while the x86 versions use a mishmash of int, unsigned (int), long and unsigned long. Using the generic version does give a slightly bigger kernel, though. defconfig: text data bss dec hex filename x86-specific: 4738555 481232 626688 5846475 5935cb vmlinux (32 bit) generic: 4738621 481232 626688 5846541 59360d vmlinux (32 bit) x86-specific: 5392395 846568 724424 6963387 6a40bb vmlinux (64 bit) generic: 5392458 846568 724424 6963450 6a40fa vmlinux (64 bit) Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/lib/bitops_32.c | 70 ------------------------------------------------ 1 file changed, 70 deletions(-) delete mode 100644 arch/x86/lib/bitops_32.c (limited to 'arch/x86/lib/bitops_32.c') diff --git a/arch/x86/lib/bitops_32.c b/arch/x86/lib/bitops_32.c deleted file mode 100644 index b65440459859..000000000000 --- a/arch/x86/lib/bitops_32.c +++ /dev/null @@ -1,70 +0,0 @@ -#include <linux/bitops.h> -#include <linux/module.h> - -/** - * find_next_bit - find the next set bit in a memory region - * @addr: The address to base the search on - * @offset: The bitnumber to start searching at - * @size: The maximum size to search - */ -int find_next_bit(const unsigned long *addr, int size, int offset) -{ - const unsigned long *p = addr + (offset >> 5); - int set = 0, bit = offset & 31, res; - - if (bit) { - /* - * Look for nonzero in the first 32 bits: - */ - __asm__("bsfl %1,%0\n\t" - "jne 1f\n\t" - "movl $32, %0\n" - "1:" - : "=r" (set) - : "r" (*p >> bit)); - if (set < (32 - bit)) - return set + offset; - set = 32 - bit; - p++; - } - /* - * No set bit yet, search remaining full words for a bit - */ - res = find_first_bit (p, size - 32 * (p - addr)); - return (offset + set + res); -} -EXPORT_SYMBOL(find_next_bit); - -/** - * find_next_zero_bit - find the first zero bit in a memory region - * @addr: The address to base the search on - * @offset: The bitnumber to start searching at - * @size: The maximum size to search - */ -int find_next_zero_bit(const unsigned long *addr, int size, int offset) -{ - const unsigned long *p = addr + (offset >> 5); - int set = 0, bit = offset & 31, res; - - if (bit) { - /* - * Look for zero in the first 32 bits. - */ - __asm__("bsfl %1,%0\n\t" - "jne 1f\n\t" - "movl $32, %0\n" - "1:" - : "=r" (set) - : "r" (~(*p >> bit))); - if (set < (32 - bit)) - return set + offset; - set = 32 - bit; - p++; - } - /* - * No zero yet, search remaining full bytes for a zero - */ - res = find_first_zero_bit(p, size - 32 * (p - addr)); - return (offset + set + res); -} -EXPORT_SYMBOL(find_next_zero_bit); -- cgit v1.2.2