A cleaned up fork of ngrep for OpenBSD
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commit c0213e3e134574abdf7a0c4ba1e918217ba340af
parent 6047bc60b7c09f63a9fbe4c9e165b252c2e63352
Author: Jordan Ritter <>
Date:   Wed,  6 Sep 2017 11:35:36 -0700

docs: regex speed test no longer relevant

Ddoc/REGEX.txt | 57---------------------------------------------------------
1 file changed, 0 insertions(+), 57 deletions(-)

diff --git a/doc/REGEX.txt b/doc/REGEX.txt @@ -1,57 +0,0 @@ -Date: 2/21/05 - -A note about PCRE vs. GNU regex: - - I ran several tests comparing GNU regex 0.12 to the PCRE 5.0 - library using 100 million loop iterations: optimized - vs. non-optimized, match vs. non-match. The obvious conclusion - is that GNU regex is the reigning king of speed, and that with - regular expression engines optimization matters significantly. - - (Please note that I tried other third-party regex libraries like - RxSpencer's and libhackerlab's, and none came close to - comparing.) - - The test subject was "how now brown cow", and the pattern we - were searching for in the match case was "now brown", and in the - non-match case "not brown". Obviously, the speed of matches is - directly related to the actual regex itself, and a - well-formulated regex certainly performs more efficiently than a - simple substring match. However, this test is reasonably - indicative of how most people use ngrep, so the test results are - still useful. - - Granted, on the single-match level the time difference is - absolutely unnoticeable (it took 100 million loop iterations to - compute something worthwhile), so this may not mean anything to - you. Likewise, the stripped binary sizes are also within 10k of - each other on the test compile box. - - If licensing terms are more sensitive for you than speed then - compile against PCRE, which is available under the Artistic - License (Free as in Beer). Otherwise, in all other cases the - GNU regex library is the best candidate, and the speed can - really help when piping those 500MB pcap dump files through - ngrep over and over for analysis. - - -Test results: - - CPU: Intel Pentium-M 2GHz - L1 I cache: 32K, L1 D cache: 32K - L2 cache: 2048K - - Iterations: 100M - - match nomatch - - [-O0] - GNU regex-0.12 17.369s/17.385s 32.656s/32.069s - PCRE-5.0 35.840s/35.795s 25.340s/25.344s - - [-O2] - GNU regex-0.12 12.240s/12.280s 19.512s/19.489s - PCRE-5.0 24.580s/24.578s 17.235s/17.238s - - -