GNU bug report logs - #17700
[PATCH] dfa: speed-up for a pattern that many atoms are catenated

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
Subject: bug#17700: closed (Re: bug#17700: [PATCH] dfa: speed-up for a
 pattern that many atoms are catenated)
Date: Fri, 06 Jun 2014 13:20:03 +0000

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Your bug report

#17700: [PATCH] dfa: speed-up for a pattern that many atoms are catenated

which was filed against the grep package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 17700 <at> debbugs.gnu.org.

-- 
17700: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=17700
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Aharon Robbins <arnold <at> skeeve.com>, 17700-done <at> debbugs.gnu.org
Subject: Re: bug#17700: [PATCH] dfa: speed-up for a pattern that many atoms
 are catenated
Date: Fri, 06 Jun 2014 22:19:13 +0900

Paul Eggert wrote:
> So it looks like your patch confers some advantage, but on my platform
> almost all the speedup is achieved simply by switching to the system strstr.

First, I tested on CentOS 5.10.  Next, I tested on RHEL 6.5, and get
result as same as you.  strstr() on CentOS 5.10 may be too old.  I'm
sure that this bug has already been fixed.  So closing.

Thanks,
Norihiro

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: bug-grep <at> gnu.org
Subject: [PATCH] dfa: speed-up for a pattern that many atoms are catenated
Date: Thu, 05 Jun 2014 20:32:44 +0900

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When many atoms are catenated, dfamust() is very slow in order that
pushing a string into `in' list is slow.  This change fixes it.

I tested below to confirm the effect.

  $ printf '%08192d\n' 0 | time -p src/grep -f - /dev/null

[0001-dfa-speed-up-for-a-pattern-that-many-atoms-are-caten.patch (text/plain, attachment)]

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