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Date: Thu, 02 Sep 2010 13:46:22 +0800 From: Miao Xie <miaox@...fujitsu.com> To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, "Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca>, Chris Mason <chris.mason@...cle.com>, Yan Zheng <zheng.yan@...cle.com> CC: Linux Kernel <linux-kernel@...r.kernel.org>, Linux Btrfs <linux-btrfs@...r.kernel.org>, Linux Ext4 <linux-ext4@...r.kernel.org> Subject: [PATCH 2/3] lib: improve the performance of memcpy and memmove of the general version the performance of memcpy and memmove of the general version is very inefficient, this patch improved them. Signed-off-by: Miao Xie <miaox@...fujitsu.com> --- lib/string.c | 32 ++++++++++++++------------------ 1 files changed, 14 insertions(+), 18 deletions(-) diff --git a/lib/string.c b/lib/string.c index f71bead..6cbf6d8 100644 --- a/lib/string.c +++ b/lib/string.c @@ -23,6 +23,7 @@ #include <linux/string.h> #include <linux/ctype.h> #include <linux/module.h> +#include <linux/memcopy.h> #ifndef __HAVE_ARCH_STRNICMP /** @@ -567,11 +568,12 @@ EXPORT_SYMBOL(memset); */ void *memcpy(void *dest, const void *src, size_t count) { - char *tmp = dest; - const char *s = src; + unsigned long dstp = (unsigned long)dest; + unsigned long srcp = (unsigned long)src; + + /* Copy from the beginning to the end */ + mem_copy_fwd(dstp, srcp, count); - while (count--) - *tmp++ = *s++; return dest; } EXPORT_SYMBOL(memcpy); @@ -588,21 +590,15 @@ EXPORT_SYMBOL(memcpy); */ void *memmove(void *dest, const void *src, size_t count) { - char *tmp; - const char *s; - - if (dest <= src) { - tmp = dest; - s = src; - while (count--) - *tmp++ = *s++; + unsigned long dstp = (unsigned long)dest; + unsigned long srcp = (unsigned long)src; + + if (dest - src >= count) { + /* Copy from the beginning to the end */ + mem_copy_fwd(dstp, srcp, count); } else { - tmp = dest; - tmp += count; - s = src; - s += count; - while (count--) - *--tmp = *--s; + /* Copy from the end to the beginning */ + mem_copy_bwd(dstp, srcp, count); } return dest; } -- 1.7.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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