GNU bug report logs - #16893
[PATCH] Avoid matching line-by-line for case-insensitive with grep

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
Subject: bug#16893: closed (Re: bug#16893: [PATCH] Avoid matching
 line-by-line for case-insensitive with grep)
Date: Sat, 01 Mar 2014 06:27:04 +0000

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Your bug report

#16893: [PATCH] Avoid matching line-by-line for case-insensitive with grep

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 16893 <at> debbugs.gnu.org.

-- 
16893: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=16893
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: 16893-done <at> debbugs.gnu.org
Subject: Re: bug#16893: [PATCH] Avoid matching line-by-line for
 case-insensitive with grep
Date: Fri, 28 Feb 2014 22:26:36 -0800

Thanks, I applied that.  It simplifies another patch I've been meaning 
to put in, yay!

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: submit <at> debbugs.gnu.org
Subject: [PATCH] Avoid matching line-by-line for case-insensitive with grep
Date: Fri, 28 Feb 2014 01:02:40 +0900

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Now grep and awk matchers doesn't waste buffer in case-sensisitive matching.
So I think that we can avoid line-by-line matching for them.

It enable to speed up case-sensitive matching with grep or awk matcher
without trivial_case_ignore as fast as when with it.

In bug#16232:
> The following times 2.16, 2.17 and 2.17+patch two ways:
> 
> $ yes jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj | head -10000000 > k
> $ for i in 16 17 18; do echo $i; env LC_ALL=en_US.UTF-8 time
> /p/p/grep-2.$i/bin/grep -i foobar k; done
> 16
>        15.96 real        14.57 user         0.12 sys
> 17
>         1.13 real         1.07 user         0.06 sys
> 18
>         1.96 real         1.89 user         0.06 sys
> 
> The above search takes more than 70% longer with the proposed patch.

Therefore, I think 30% slow-down is caused by the line-by-line matching
for them.

[avoid_line_by_line.txt (application/octet-stream, attachment)]

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