On Fri, 13 Aug 2010, Gabor Kovesdan wrote: > Em 2010.08.13. 10:43, Doug Barton escreveu: >> My reason is simple, performance. While doing some portmaster work >> recently I was regression testing some changes I made to the --index* >> options and noticed that things were dramatically slower than the >> last time I tested those features. Thinking that I had made a >> programming mistake I dug into my code, and while the regexps that I >> was using could be tuned for slightly better performance the problem >> was not in my code. I then installed textproc/gnugrep to compare, >> and the differences were very dramatic using a highly pessimized test >> case (finding a match on the last line of INDEX). The script I used >> to test is at http://people.freebsd.org/~dougb/grep-time-trial.sh.txt >> and a typical result was: >> >> GNU grep >> Elapsed time: 2 seconds >> >> BSD grep >> Elapsed time: 47 seconds >> > Ok, I'll take care of this soon, and make GNU grep default, again with > a knob to build BSD grep. I agree with you that we cannot allow such a > big performance drawback but I my measures only showed significant > differences for very big searches and I didn't imagine that it could > add up to such a big diference. I'm sorry for the bad decision I took > making it default. This should trim some time off BSD grep. It removes the lock/unlock for each fgetc() by locking/unlocking the file once. stdio can be slow. You probably want to replace flockfile() with ftrylockfile() if threads will be involved at some point (threading or making a libgrep that may be used in a threaded process). Sean -- scf_at_FreeBSD.org
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