NAME¶
Smokeping::matchers::Medratio - detect changes in the latency median
OVERVIEW¶
The Medratio matcher establishes a historic median latency over several
measurement rounds. It compares this median, against a second median latency
value again build over several rounds of measurement.
By looking at the median value this matcher is largly imune against spikes and
will only react to long term developments.
DESCRIPTION¶
Call the matcher with the following sequence:
type = matcher
pattern = Medratio(historic=>a,current=>b,comparator=>o,percentage=>p)
- historic
- The number of values to use for building the 'historic' median.
- current
- The number of values to use for building the 'current' median.
- comparator
- Which comparison operator should be used to compare current/historic with
percentage.
- percentage
- Right hand side of the comparison.
old <--- historic ---><--- current ---> now
EXAMPLE¶
Take the 12 last median values. Build the median out of the first 10 and the
median from the other 2 values. Divide the results and decide if it is bigger
than 150 percent.
Medratio(historic=>10,current=>2,comparator=>'>',percentage=>150);
med(current)/med(historic) > 150/100
This means the matcher will activate when the current latency median is more
than 1.5 times the historic latency median established over the last 10 rounds
of measurement.
COPYRIGHT¶
Copyright (c) 2006 by OETIKER+PARTNER AG. All rights reserved.
The development of this matcher has been paied for by Virtela Communications,
<
http://www.virtela.net/>.
LICENSE¶
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 675 Mass
Ave, Cambridge, MA 02139, USA.
AUTHOR¶
Tobias Oetiker <tobi@oetiker.ch>