commit c0213e3e134574abdf7a0c4ba1e918217ba340af
parent 6047bc60b7c09f63a9fbe4c9e165b252c2e63352
Author: Jordan Ritter <jpr5@darkridge.com>
Date: Wed, 6 Sep 2017 11:35:36 -0700
docs: regex speed test no longer relevant
Diffstat:
| D | doc/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
-
-
-