From: linux@horizon.com
To: git@vger.kernel.org, junkio@cox.net
Cc: linux@horizon.com
Subject: Re: x86 asm SHA1 (draft)
Date: 23 Jun 2006 21:22:02 -0400 [thread overview]
Message-ID: <20060624012202.4822.qmail@science.horizon.com> (raw)
In-Reply-To: <7vzmg376ee.fsf@assigned-by-dhcp.cox.net>
> The series to revamp SHA1 is good but judging the merit of each
> is outside my expertise, so I'd appreciate help to evaluate
> these changes. For example, I cannot choose between competing
> three implementations for ppc without having access to a variety
> of ppc machines, and even if I did, ppc is not what I normally
> use, so incentive to try picking the best one for everybody is
> relatively low on my part.
Well, I'm not sure it's worth this much trouble. Both of my PPC
implementations are smaller and faster than the current one,
so that's a pretty easy decision. The difference between them
is 2-3%, which is, I think, not enough to be worth the maintenance
burden of a run-time decision infrastructure. Just pick either one
and call it a day.
> The only external interface for the set of SHA1 implementation
> alternatives to the outside world is a well established SHA_CTX
> type, and three functions SHA1_Init(), SHA1_Update() and
> SHA1_Final(), and the alternative implementations are supposed
> to be drop-in replaceable.
I'd prefer it it was an *opaque* SHA_CTX type. Sometimes you can achieve
some useful benefits by rearranging the fields. For example, keeping the
64-bit length field as a native-order 64-bit number when appropriate.
And sometimes it's useful to have the full 80-word W[] array, while
other implementations don't want it.
> We probably would want to collect the benchmark results from
> popular platforms, have a summary to help people to choose a
> sensible one in the toplevel INSTALL file, and include the raw
> numbers in Documentation/technical/sha1-implementations.txt.
Not that numbers are bad, but I think that until there's a real
need for more than a single good-enough version per instruction set,
this is excessive. Does hashing even show up on a profile?
next prev parent reply other threads:[~2006-06-24 6:47 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-23 17:18 x86 asm SHA1 (draft) linux
2006-06-24 0:18 ` Junio C Hamano
2006-06-24 1:22 ` linux [this message]
2006-06-24 7:03 ` Junio C Hamano
2006-06-24 7:59 ` From b65bc21e7d8dc8cafc70dfa6354cb66b8874b2d9 Mon Sep 17 00:00:00 2001, [PATCH] Makefile: add framework to verify and bench sha1 implementations Junio C Hamano, Junio C Hamano
2006-06-24 9:29 ` From b65bc21e7d8dc8cafc70dfa6354cb66b8874b2d9 Mon Sep 17 00:00:00 2001 " linux
2006-06-24 19:47 ` Junio C Hamano
2006-06-24 9:20 ` x86 asm SHA1 (draft) linux
2006-06-24 10:03 ` PPC SHA-1 Updates in "pu" Junio C Hamano
2006-06-24 18:55 ` Linus Torvalds
2006-06-24 20:21 ` Junio C Hamano
2006-06-24 20:42 ` Linus Torvalds
2006-06-24 23:59 ` Junio C Hamano
2006-06-25 1:02 ` Petr Baudis
2006-06-25 1:40 ` [PATCH] Git.pm build: Fix quoting and missing GIT-CFLAGS dependency Petr Baudis
2006-06-25 3:03 ` Junio C Hamano
2006-06-25 15:21 ` Petr Baudis
2006-06-26 6:48 ` Junio C Hamano
2006-07-01 23:59 ` [POOL] Who likes running Git without make install? Petr Baudis
2006-07-02 0:05 ` Junio C Hamano
2006-07-02 0:08 ` Junio C Hamano
2006-07-02 11:30 ` Petr Baudis
2006-07-02 17:19 ` Junio C Hamano
2006-07-03 6:54 ` [POLL] " Junio C Hamano
2006-07-03 7:58 ` Petr Baudis
2006-07-03 8:08 ` Junio C Hamano
2006-07-03 8:17 ` Petr Baudis
2006-07-03 8:37 ` Johannes Schindelin
2006-06-25 1:24 ` PPC SHA-1 Updates in "pu" Petr Baudis
2006-06-25 3:57 ` Junio C Hamano
2006-06-25 9:34 ` Petr Baudis
2006-06-25 10:07 ` Johannes Schindelin
2006-06-25 10:20 ` Petr Baudis
2006-06-25 10:48 ` Junio C Hamano
2006-06-25 13:44 ` Johannes Schindelin
2006-06-25 18:46 ` Randal L. Schwartz
2006-06-25 23:23 ` Johannes Schindelin
2006-06-26 1:51 ` perl profiling (was: PPC SHA-1 Updates in "pu") Jeff King
2006-06-26 6:49 ` PPC SHA-1 Updates in "pu" Junio C Hamano
2006-06-30 1:28 ` GIt.xs merge status Junio C Hamano
2006-06-30 5:08 ` Pavel Roskin
2006-06-30 7:18 ` Git.xs " Junio C Hamano
2006-06-30 7:28 ` Pavel Roskin
2006-06-30 9:53 ` GIt.xs " Johannes Schindelin
2006-06-30 10:26 ` Junio C Hamano
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