From: "René Scharfe" <rene.scharfe@lsrfire.ath.cx>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 3/4] diffcore-pickaxe: further refactor count_match()
Date: Sat, 28 Feb 2009 19:15:46 +0100 [thread overview]
Message-ID: <49A97F52.4080405@lsrfire.ath.cx> (raw)
In-Reply-To: <7vmyc6foj3.fsf@gitster.siamese.dyndns.org>
Junio C Hamano schrieb:
> René Scharfe <rene.scharfe@lsrfire.ath.cx> writes:
>
>> I get this (Ubuntu 8.10 x64, Fedora 10 x64 using the same Linux repo,
>> Windows Vista x64 using a different Linux repo with the same HEAD on
>> NTFS and msysgit, numbers are the elapsed time in seconds, best of five
>> runs):
>>
>> Ubuntu Fedora Windows
>> v1.6.2-rc2 8.14 8.16 9.236
>> v1.6.2-rc2+[1-4] 2.43 2.45 2.995
>> v1.6.2-rc2+[1-4]+memmem 1.31 1.25 2.917
>> v1.6.2-rc2+[1-3]+memmem 1.51 1.16 8.455
>>
>> Ubuntu has glibc 2.8, while Fedora 10 has glibc 2.9, with a new and more
>> efficient memmem() implementation. On Windows, we use our own naive
>> memmem() implementation.
>
> Yeah, what does glibc use these days? Some variant of Boyer-Moore?
No, the algorithm is called Two Way, which, unlike Boyer-Moore, only
needs constant space. The implementation seems to originate from this bug:
http://sourceware.org/bugzilla/show_bug.cgi?id=5514
And the algorithm is documented here:
http://www-igm.univ-mlv.fr/~lecroq/string/node26.html
René
next prev parent reply other threads:[~2009-02-28 18:17 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-26 6:52 [PATCH 0/4] Pickaxe search clean-up and optimization Junio C Hamano
2009-02-26 6:52 ` [PATCH 1/4] diffcore-pickaxe: refactor diffcore_pickaxe() Junio C Hamano
2009-02-27 23:58 ` René Scharfe
2009-02-26 6:52 ` [PATCH 2/4] diffcore-pickaxe: micro-optimize has_match() function Junio C Hamano
2009-02-26 6:52 ` [PATCH 3/4] diffcore-pickaxe: further refactor count_match() Junio C Hamano
2009-02-26 7:23 ` Kjetil Barvik
2009-02-28 1:13 ` René Scharfe
2009-02-28 1:25 ` Junio C Hamano
2009-02-28 6:08 ` Junio C Hamano
2009-02-28 13:10 ` René Scharfe
2009-02-28 17:40 ` Junio C Hamano
2009-02-28 18:15 ` René Scharfe [this message]
2009-02-28 19:16 ` [PATCH] import memmem() with linear complexity from Gnulib René Scharfe
2009-02-28 22:44 ` Mike Hommey
2009-03-01 3:41 ` Jeff King
2009-03-01 11:15 ` René Scharfe
2009-03-01 18:55 ` René Scharfe
2009-03-01 7:31 ` [PATCH 3/4] diffcore-pickaxe: further refactor count_match() Junio C Hamano
2009-03-01 10:53 ` René Scharfe
2009-02-26 6:52 ` [PATCH 4/4] diffcore-pickaxe: optimize by trimming common initial and trailing parts Junio C Hamano
2009-02-26 9:05 ` Junio C Hamano
2009-03-02 23:00 ` [PATCH 1/2] diffcore-pickaxe: use memmem() René Scharfe
2009-03-02 23:19 ` [PATCH 2/2] optimize compat/ memmem() René Scharfe
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