It should be more efficient to use nicely aligned buffer sizes, either
for filesystem operations or SHA1 checksums. Also, using a relatively
small nominal size might allow for the data to remain in L1 cache
between both SHA1_Update() calls.
Signed-off-by: Nicolas Pitre <nico@xxxxxxx>
---
pack-write.c | 11 ++++++++---
1 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/pack-write.c b/pack-write.c
index f9776c5..939ed56 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -167,7 +167,7 @@ void fixup_pack_header_footer(int pack_fd,
unsigned char *partial_pack_sha1,
off_t partial_pack_offset)
{
- static const int buf_sz = 128 * 1024;
+ int aligned_sz, buf_sz = 8 * 1024;
SHA_CTX old_sha1_ctx, new_sha1_ctx;
struct pack_header hdr;
char *buf;
@@ -188,10 +188,11 @@ void fixup_pack_header_footer(int pack_fd,
partial_pack_offset -= sizeof(hdr);
buf = xmalloc(buf_sz);
+ aligned_sz = buf_sz - sizeof(hdr);
for (;;) {
ssize_t m, n;
- m = (partial_pack_sha1 && partial_pack_offset < buf_sz) ?
- partial_pack_offset : buf_sz;
+ m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
+ partial_pack_offset : aligned_sz;
n = xread(pack_fd, buf, m);
if (!n)
break;
@@ -199,6 +200,10 @@ void fixup_pack_header_footer(int pack_fd,
die("Failed to checksum %s: %s", pack_name, strerror(errno));
SHA1_Update(&new_sha1_ctx, buf, n);
+ aligned_sz -= n;
+ if (!aligned_sz)
+ aligned_sz = buf_sz;
+
if (!partial_pack_sha1)
continue;
--
1.6.0.1.212.g35f9f
--
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