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hash-object: don't use mmap() for small files 

Using read() instead of mmap() can be 39% speed up for 1Kb files and is
1% speed up 1Mb files. For larger files, it is better to use mmap(),
because the difference between is not significant, and when there is not
enough memory, mmap() performs much better, because it avoids swapping.

Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Dmitry Potapov 2010-02-21 09:32:19 +03:00 committed by Junio C Hamano
parent e923eaeb90
commit ea68b0ce9f
1 changed files with 10 additions and 0 deletions
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10
sha1_file.c
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@ -2434,6 +2434,8 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
return ret;
}
#define SMALL_FILE_SIZE (32*1024)
int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
enum object_type type, const char *path)
{
@ -2448,6 +2450,14 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
else
ret = -1;
strbuf_release(&sbuf);
} else if (size <= SMALL_FILE_SIZE) {
char *buf = xmalloc(size);
if (size == read_in_full(fd, buf, size))
ret = index_mem(sha1, buf, size, write_object, type,
path);
else
ret = error("short read %s", strerror(errno));
free(buf);
} else if (size) {
void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
ret = index_mem(sha1, buf, size, write_object, type, path);