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From: | Paul Eggert |
Subject: | bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching |
Date: | Wed, 23 Apr 2014 23:33:13 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 |
Norihiro Tanaka wrote:
could you also test below for master and original grep-2.18? $ yes abcdabc | head -50000000 >../k $ env LANG=C time -p src/grep abcd.bd ../k Perhaps, later will be faster.
Yes, grep 2.18 is a bit faster on that benchmark for me; it's about 3.6s real-time, whereas the master is about 4.2s.
0001-grep-speed-up-by-replacing-incr-to-add-in-x86-and-x8.patch will fix it. delta2 searching is higher cost than mind2 searching in original grep-2.18. We need to reduce it for delta2 searching.
Unfortunately it doesn't help for me; it causes the same benchmark to take about 4.3s real-time. Here, I am talking about the version resulting from applying the patch in <http://debbugs.gnu.org/cgi/bugreport.cgi?msg=22;filename=17230.diff;att=1;bug=17230> to the master.
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