On Fri, Jul 30, 1999 at 03:27:20PM +0200, Dag-Erling Smorgrav wrote: > > Funnily, I experience a near-doubling of running time with similar > patches.
Incidentally, it seems that it's not possible to assume that our regex library is even anywhere in the same league as the GNU regex library. b$ time ./grep -E '(vt100)|(printer)' longfile > /dev/null real 0m21.284s user 0m22.034s sys 0m0.083s Now, with a profiled executable with optimization turned off it takes about 25 seconds. Regardless, it appears to spend 98% of its time in regexec(), which is good, since that's where it should be spending time. [I had been intending to combine multiple patterns, ultimately combining in a '\n' to avoid the memchr() in mmopen]. b$ time grep '(vt100)|(printer)' longfile > /dev/null real 0m0.267s user 0m0.109s sys 0m0.157s 98% * 20 = ~19... Without an improved regex library, any mildly complicated pattern will bring the new grep to its knees. This could be the dfa helping GNU grep more than having a better regexp library... Probably both. I wonder how well the devel/pcre port would do POSIX regular expressions. -- This is my .signature which gets appended to the end of my messages. To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
