From: "George Spelvin" <linux@horizon.com>
To: jonsmirl@gmail.com
Cc: git@vger.kernel.org, linux@horizon.com
Subject: Re: x86 SHA1: Faster than OpenSSL
Date: 4 Aug 2009 01:01:38 -0400 [thread overview]
Message-ID: <20090804050138.13256.qmail@science.horizon.com> (raw)
In-Reply-To: <9e4733910908032007td74ef9fp669d0d958df67c1@mail.gmail.com>
> Would there happen to be a SHA1 implementation around that can compute
> the SHA1 without first decompressing the data? Databases gain a lot of
> speed by using special algorithms that can directly operate on the
> compressed data.
I can't imagine how. In general, this requires that the compression
be carefully designed to be compatible with the algorithms, and SHA1
is specifically designed to depend on every bit of the input in
an un-analyzable way.
Also, git normally avoids hashing objects that it doesn't need
uncompressed for some other reason. git-fsck is a notable exception,
but I think the idea of creating special optimized code paths for that
interferes with its reliability and robustness goals.
next prev parent reply other threads:[~2009-08-04 5:01 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-26 23:21 Performance issue of 'git branch' George Spelvin
2009-07-31 10:46 ` Request for benchmarking: x86 SHA1 code George Spelvin
2009-07-31 11:11 ` Erik Faye-Lund
2009-07-31 11:31 ` George Spelvin
2009-07-31 11:37 ` Michael J Gruber
2009-07-31 12:24 ` Erik Faye-Lund
2009-07-31 12:29 ` Johannes Schindelin
2009-07-31 12:32 ` George Spelvin
2009-07-31 12:45 ` Erik Faye-Lund
2009-07-31 13:02 ` George Spelvin
2009-07-31 11:21 ` Michael J Gruber
2009-07-31 11:26 ` Michael J Gruber
2009-07-31 12:31 ` Carlos R. Mafra
2009-07-31 13:27 ` Brian Ristuccia
2009-07-31 14:05 ` George Spelvin
2009-07-31 13:27 ` Jakub Narebski
2009-07-31 15:05 ` Peter Harris
2009-07-31 15:22 ` Peter Harris
2009-08-03 3:47 ` x86 SHA1: Faster than OpenSSL George Spelvin
2009-08-03 7:36 ` Jonathan del Strother
2009-08-04 1:40 ` Mark Lodato
2009-08-04 2:30 ` Linus Torvalds
2009-08-04 2:51 ` Linus Torvalds
2009-08-04 3:07 ` Jon Smirl
2009-08-04 5:01 ` George Spelvin [this message]
2009-08-04 12:56 ` Jon Smirl
2009-08-04 14:29 ` Dmitry Potapov
2009-08-18 21:50 ` Andy Polyakov
2009-08-04 4:48 ` George Spelvin
2009-08-04 6:30 ` Linus Torvalds
2009-08-04 8:01 ` George Spelvin
2009-08-04 20:41 ` Junio C Hamano
2009-08-05 18:17 ` George Spelvin
2009-08-05 20:36 ` Johannes Schindelin
2009-08-05 20:44 ` Junio C Hamano
2009-08-05 20:55 ` Linus Torvalds
2009-08-05 23:13 ` Linus Torvalds
2009-08-06 1:18 ` Linus Torvalds
2009-08-06 1:52 ` Nicolas Pitre
2009-08-06 2:04 ` Junio C Hamano
2009-08-06 2:10 ` Linus Torvalds
2009-08-06 2:20 ` Nicolas Pitre
2009-08-06 2:08 ` Linus Torvalds
2009-08-06 3:19 ` Artur Skawina
2009-08-06 3:31 ` Linus Torvalds
2009-08-06 3:48 ` Linus Torvalds
2009-08-06 4:01 ` Linus Torvalds
2009-08-06 4:28 ` Artur Skawina
2009-08-06 4:50 ` Linus Torvalds
2009-08-06 5:19 ` Artur Skawina
2009-08-06 7:03 ` George Spelvin
2009-08-06 4:52 ` George Spelvin
2009-08-06 4:08 ` Artur Skawina
2009-08-06 4:27 ` Linus Torvalds
2009-08-06 5:44 ` Artur Skawina
2009-08-06 5:56 ` Artur Skawina
2009-08-06 7:45 ` Artur Skawina
2009-08-06 18:49 ` Erik Faye-Lund
2009-08-04 6:40 ` Linus Torvalds
2009-08-18 21:26 ` Andy Polyakov
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