Date: Sat, 14 Aug 2010 11:03:50 +0300 From: Daniel Braniss <danny@cs.huji.ac.il> To: "Sean C. Farley" <scf@FreeBSD.org> Cc: Gabor Kovesdan <gabor@FreeBSD.org>, current@FreeBSD.org Subject: Re: Official request: Please make GNU grep the default Message-ID: <E1OkBiZ-0004f1-0L@kabab.cs.huji.ac.il> In-Reply-To: <alpine.BSF.2.00.1008131034440.35204@thor.farley.org> References: <4C6505A4.9060203@FreeBSD.org> <4C650B75.3020800@FreeBSD.org> <alpine.BSF.2.00.1008131034440.35204@thor.farley.org>
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> This message is in MIME format. The first part should be readable text, > while the remaining parts are likely unreadable without MIME-aware tools. > > --56599777-398594934-1281714095=:35204 > Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed > > 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). why would you want to lock a file for reading anyways? BTW, back in the jurasic age, ATT/Bell had this poster: Reach out and GREP someone! danny
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