#!/usr/bin/perl -wT
#
# ctrl_athcool.pl
# Version: 1.0.2 25-FEB-2008
# Author:  David Mathog, Biology Division, Caltech
# Contact: mathog@caltech.edu
# Copyright: 2007, David Mathog and Caltech
#
# This procedure keeps on eye on how busy the system is and
# toggles athcool on or off.  If the system is busy, it turns it
# off, and if it is slow it turns it on.  This enables power saving
# on a more or less idle system, without sacrificing (much) performance when
# the system is busy.
#
# It looks ONLY at the idle time in /proc/stat.  The higher that value per
# second the more idle the system is, the lower that value per second, the more
# busy the system is.  Start this as a daemon when athcool starts.
#
# v1.0.2 fixed bug
# v1.0.1 added support for toggling athcool on heavy network load
# v1.0.0 first version
#
# Parameters are:
#   None, values are hardwired in here
#
#####################################################################
# License terms:
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
####################################################################

use strict;
####################################################################
# site specific values, modify to fit your site!!!!
#
delete @ENV{'ENV', 'BASH_ENV'};  #or -T complains
$ENV{PATH}        = '/bin:/usr/bin:/usr/local/bin';
my $STATFILE      = '/proc/stat';
my $NETFILE       = '/proc/net/dev';
my $ATHCOOL       = '/usr/sbin/athcool';
my $INTERVAL      = 1;  # time sampling interval in seconds
my $IDLE_DOWN     = 50; # threshold for idle measurement going down (indicates an idle -> busy system)
my $IDLE_UP       = 70; # threshold for idle measurement going up   (indicates a busy -> idle system) 
my $DELTAP_DOWN   = 1000; # threshold for packet rate measurement going down (indicates a busy -> idle system)
my $DELTAP_UP     = 2000; # threshold for idle measurement going up   (indicates an idle -> busy system) 
my $DELAY_OFF     = 0;  # seconds it must be busy (below IDLE_DOWN or above DELTAP_UP) before turning athcool off
my $DELAY_ON      = 3;  # seconds it must be idle (above IDLE_UP AND DELTAP_DOWN)   before turning athcool on
####################################################################
#
# Do not modify anything below this point
#
my $lastidle=0;     #idle time info from last interval
my $lastp=0;        #sum packets
my $idle=0;         #cumulative idle time
my $packets=0;
my $deltap=0;
my $idif;           #idle time info from this interval 0 = busy, 100 is all idle, may read 101
my $line;
my @chunks;
my $discard_text;
my $count_off  = $DELAY_OFF;
my $count_on   = $DELAY_ON;

# start athcool (script must know what state athcool is in, harmless if athcool is already running)
my $athcool_state = 1; 
$discard_text= `$ATHCOOL on`;
while (1) {
   open (SFILE, "<$STATFILE") or die;
   $line = <SFILE>;
   close(SFILE);
   @chunks = split(" ",$line);   #0 is "CPU" string
   $idle  = $chunks[4];  #Time in idle state
   
   open (SFILE, "<$NETFILE") or die;
   while(<SFILE>){
     $line = <SFILE>;
     if($line =~ m/eth0/){
        @chunks = split(" ",$line);   #0 is "ETH0" string
        $packets  = $chunks[1] + $chunks[9];  #Time in idle state
        $deltap   = $packets - $lastp;  #garbage on first cycle, but not used on first cycle
        $lastp    = $packets;
     }
   }
   close(SFILE);
   
   if($lastidle == 0){ 
     $lastidle = $idle;  # and don't shift anything
   }
   else {
     $idif = $idle - $lastidle;  # fraction of time idle 0 to 100 (more or less)
     $lastidle = $idle;

#     print "DEBUG idif $idif  deltap $deltap DELTAP_UP $DELTAP_UP DELTAP_DOWN $DELTAP_DOWN count_on $count_on count_off $count_off\n";
     if(($idif <= $IDLE_DOWN) || ($deltap >= $DELTAP_UP)){
       $count_on    = $DELAY_ON;
       $count_off -= 1;
       if($count_off <= 0){
         $count_off = 0;
         if($athcool_state == 1){
#           print "DEBUG athcool off\n";
           $discard_text= `$ATHCOOL off`;
           $athcool_state = 0;
         }
       }
     }
     elsif( ($idif >= $IDLE_UP) && ($deltap <= $DELTAP_DOWN) ){
       $count_on   -= 1;
       $count_off  = $DELAY_OFF;
       if($count_on <= 0){
         $count_on= 0;
         if($athcool_state == 0){
#           print "DEBUG athcool on\n";
           $discard_text= `$ATHCOOL on`;
           $athcool_state = 1;
         }
       }
     }
     else {
       $count_on   = $DELAY_ON;
       $count_off = $DELAY_OFF;
     }
   }
   sleep(1);
}
exit;