GNU bug report logs - #17350
[PATCH] grep: speed up for a case to repeat failure in DFA after success in kwset

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Package: grep;

Reported by: Norihiro Tanaka <noritnk <at> kcn.ne.jp>

Date: Sat, 26 Apr 2014 11:27:02 UTC

Severity: normal

Tags: patch

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

Full log

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: bug-grep <at> gnu.org
Subject: [PATCH] grep: speed up for a case to repeat failure in DFA after
 success in kwset
Date: Sat, 26 Apr 2014 20:25:43 +0900

[Message part 1 (text/plain, inline)]
Patch#17230 causes slowdown for a case to repeat failure in DFA after
success in kwset, although it improves the performance for many cases.

In fact, the master without this patch is 3.5x slower than grep 2.18 for
below.

    $ yes abcdabc | head -50000000 >k
    $ env LC_ALL=C time -p src/grep -i 'abcd.bd' k

This patch fixes the degradation of the performance for such cases.  See
the commit log for details.

Norihiro

[patch.txt (text/plain, attachment)]
This bug report was last modified 11 years and 19 days ago.

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