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From: | Paul Eggert |
Subject: | bug#17576: [PATCH] dfa: speed-up at initial state |
Date: | Fri, 23 May 2014 22:01:36 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Norihiro Tanaka wrote:
I tested the patch, and got about 3x speed-up.
That, but unfortunately whan I timed that patch against the current grep trunk (879d86e6242eae688f9e72d42b230348d1c93a8f), it slowed things down on a similar test case (a test like yours, but 100x longer).
$ yes j | head -1000000000 >k $ env LC_ALL=C time -p src/grep-old '\(a\|b\)' k real 8.25 user 7.74 sys 0.50 $ env LC_ALL=C time -p src/grep '\(a\|b\)' k real 11.11 user 10.63 sys 0.46 $ env LC_ALL=ja_JP.eucJP time -p src/grep-old '\(a\|b\)' k real 8.74 user 8.27 sys 0.43 $ env LC_ALL=ja_JP.eucJP time -p src/grep '\(a\|b\)' k real 8.95 user 8.44 sys 0.49This is on my usual platform: Fedora 20 x86-64, AMD Phenum II X4 910e, GCC 4.9.0, default (-O2) optimization.
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