[PATCH 5/5] fixup_pack_header_footer(): use nicely aligned buffer sizes
- From
Nicolas Pitre <nico@cam.org>
- Date
- Aug 29, 2008, 20:08 UTC
- Message-ID
- <1220040482-10108-6-git-send-email-nico@cam.org>
- In-Reply-To
- <1220040482-10108-5-git-send-email-nico@cam.org>
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@cam.org> --- 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