Automatic Transmission Throttle for Merlin

[Turgut Kalfaoglu]

This is the script I wrote to automatically throttle transmission based on the ping values to our uplink..
It features fast download throttling against impulse usage, and pause before re-increasing the download speed if it was recently lowered.

Feel free to use it, but you will need ooRexx installed.

#!/opt/bin/rexx
/* Automatic Transmission throttle based on the ping values from your next hop.
 By Turgut Kalfaoglu <turgut@kalfaoglu.com>
 
 Usage: start this script with the quiet option for regular use. quiet option prevents output to screen.
 For example: in /jfss/bin/services-start :
   /usr/bin/nohup /opt/bin/transmission-throttle quiet &
 may be used to start it

Requires OOrexx

Outputs to /opt/var/log/transmission-throttle.log
*/

parse arg quiet
if quiet='quiet' then quiet=1
else quiet=0

login = 'root:itspassword'    /* transmission RPC login infomation - set it in transmission config */
speed=900             /* initial speed in bps */
minspeed=10              /* minimum bps possible */
maxspeed=1500              /* maximum bps you want transmission to use       */
threshold = 70          /* in ms - we try to keep pings below this value  */
steps = 50             /* lower/increase speed by "steps" bps            */
targetip =  "71.16.10.1"  /* The IP of your uplink - at telecom. do a traceroute www.kalfaoglu.net to find out your next hop */

"/opt/bin/transmission-remote --auth" login "-d " minspeed ">/dev/null"
'/opt/bin/rxqueue /clear'
lastlowered=time('R')
lastlowered=time('E')
do forever
  setspeed=0
  "ping -W 5 -c 3" targetip "| grep round | /opt/bin/rxqueue"
  if queued()>0 then do
    oldspeed=speed
    parse pull "min/avg/max =" .'/'line'/'.
    if quiet=0 then say 'avg ping:' line 'ms'
    if line>threshold*2 then do /* is the line VERY busy? decrease it a lot */
       speed=speed-(steps*2)
       lastlowered=time('E')
       if speed<minspeed then
        speed=minspeed
       else
        if quiet=0 then say 'speed lowered by' steps*2
    end
    if line>threshold then do
       lastlowered=time('E')
       speed=speed-steps
       if speed<minspeed then
        speed=minspeed
    else
               if quiet=0 then say 'speed lowered by' steps
    end
    if line<threshold then do
        if time('E')-lastlowered>30 Then do
        speed=speed+steps
        if speed>maxspeed then
            speed=maxspeed
        else
                   if quiet=0 then say 'speed raise by' steps
    end
    else /* will not raise right after lowering it.. */
           if quiet=0 then say 'cannot raise speed yet' trunc(time('E')-lastlowered) 'secs elapsed'
    end
    if oldspeed<>speed then do
        if quiet=0 then say 'speed changed.. setting transmission to ' speed
       '/opt/bin/transmission-remote --auth' login '-d' speed '>/dev/null'
       'echo' date() time() 'ping' line 'current speed' speed '>> /opt/var/log/transmission-throttle.log'
    end
   end
   '/opt/bin/rxqueue /clear'
   'sleep 5s'
end