From 68f4d5a00adaab33b136fce2c72d5c377b39b0b0 Mon Sep 17 00:00:00 2001 From: Zhao Yakui Date: Fri, 8 Oct 2010 09:47:33 +0800 Subject: [PATCH] x86, setup: Use string copy operation to optimze copy in kernel compression The kernel decompression code parses the ELF header and then copies the segment to the corresponding destination. Currently it uses slow byte-copy code. This patch makes it use the string copy operations instead. In the test the copy performance can be improved very significantly after using the string copy operation mechanism. 1. The copy time can be reduced from 150ms to 20ms on one Atom machine 2. The copy time can be reduced about 80% on another machine The time is reduced from 7ms to 1.5ms when using 32-bit kernel. The time is reduced from 10ms to 2ms when using 64-bit kernel. Signed-off-by: Zhao Yakui LKML-Reference: <1286502453-7043-1-git-send-email-yakui.zhao@intel.com> Signed-off-by: H. Peter Anvin --- arch/x86/boot/compressed/misc.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 8f7bef8..23f315c 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -229,18 +229,35 @@ void *memset(void *s, int c, size_t n) ss[i] = c; return s; } - +#ifdef CONFIG_X86_32 void *memcpy(void *dest, const void *src, size_t n) { - int i; - const char *s = src; - char *d = dest; + int d0, d1, d2; + asm volatile( + "rep ; movsl\n\t" + "movl %4,%%ecx\n\t" + "rep ; movsb\n\t" + : "=&c" (d0), "=&D" (d1), "=&S" (d2) + : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src) + : "memory"); - for (i = 0; i < n; i++) - d[i] = s[i]; return dest; } +#else +void *memcpy(void *dest, const void *src, size_t n) +{ + long d0, d1, d2; + asm volatile( + "rep ; movsq\n\t" + "movq %4,%%rcx\n\t" + "rep ; movsb\n\t" + : "=&c" (d0), "=&D" (d1), "=&S" (d2) + : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src) + : "memory"); + return dest; +} +#endif static void error(char *x) { -- 2.7.4