Smokeping::matchers::Medratio(3)   SmokePing  Smokeping::matchers::Medratio(3)



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/his-
           toric 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.

SPONSORSHIP
       The development of this matcher has been paied for by Virtela Communi-
       cations, <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 MER-
       CHANTABILITY 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>



2.4.2                             2006-12-12  Smokeping::matchers::Medratio(3)
