Re: [PATCH] Disable OpenSSL SHA1 implementation by default

From: Mark Lodato <lodatom@gmail.com>
Date: Feb 26, 2010, 04:11 UTC
Message-ID: <ca433831002252011r3d3459a2xca7535300cd6630f@mail.gmail.com>
In-Reply-To: <20100222112326.GA21929@coredump.intra.peff.net>

On Mon, Feb 22, 2010 at 6:23 AM, Jeff King <peff@peff.net> wrote:

Show 8 quoted lines

> On Mon, Feb 22, 2010 at 05:08:14AM -0600, Jonathan Nieder wrote:
>
>> The OpenSSL SHA-1 routine is about as fast as block-sha1, but linking
>> to libcrypto slows down the startup of git commands by an appreciable
>> amount.  Use the BLK_SHA1 implementation by default instead.
>
> What is your definition of "about as fast"? I benchmarked up to a 20%
> slow-down a while back:

For what it's worth, here are my numbers from running git-fsck on my x86-64 machine. It appears that BLK-SHA1 is slightly faster. If you know a better benchmark to run, let me know. Perhaps it would be good to write some sort of suite to test this, and let people post their results to some website.

make git-fsck ./git-fsck 66.75s user 0.28s system 99% cpu 1:07.17 total ./git-fsck 66.70s user 1.28s system 99% cpu 1:08.06 total ./git-fsck 66.77s user 0.63s system 99% cpu 1:07.42 total

make BLK_SHA1=1 git-fsck ./git-fsck 65.60s user 0.65s system 99% cpu 1:06.26 total ./git-fsck 65.39s user 0.65s system 99% cpu 1:06.06 total ./git-fsck 65.24s user 1.36s system 100% cpu 1:06.60 total

Core 2 Duo E6300 1.86 GHz (2MB L2 cache), 2GB memory Ubuntu 9.10 x86-64, gcc 4.4.1, git v1.7.0-90-g251a495