Daemon runs in background and checks if some process is consuming more then 20% of CPU and if it does then daemon lowers CPU consumption of particular process to maximum of 20%. The goal is to have no single process that consumes more then 20% of CPU power.
Note: If you would like to omit only one process then you don't need this "cpulimit daemon". In this case you only need cpulimit program to be executed from terminal.
Tested environment:
Cpulimit daemon was tested on Ubuntu 8.04 LTS and Ubuntu 10.04 LTS. However it should be running fine on other Ubuntu versions and also on other Linux distributions, because it does not uses any Ubuntu specific code.
1. INSTALL PACKAGES
1. Install cpulimit package.
Code:
sudo apt-get install cpulimitCode:
sudo apt-get install gawk2. CREATE CPULIMIT DAEMON FILE
Open text editor with root privileges and save bellow daemon script text to new file /usr/bin/cpulimit_daemon.sh
Code:
#!/bin/bash
# ==============================================================
# CPU limit daemon - set PID's max. percentage CPU consumptions
# ==============================================================
# Variables
CPU_LIMIT=20 # Maximum percentage CPU consumption by each PID
DAEMON_INTERVAL=3 # Daemon check interval in seconds
BLACK_PROCESSES_LIST= # Limit only processes defined in this variable. If variable is empty (default) all violating processes are limited.
WHITE_PROCESSES_LIST= # Limit all processes except processes defined in this variable. If variable is empty (default) all violating processes are limited.
# Check if one of the variables BLACK_PROCESSES_LIST or WHITE_PROCESSES_LIST is defined.
if [[ -n "$BLACK_PROCESSES_LIST" && -n "$WHITE_PROCESSES_LIST" ]] ; then # If both variables are defined then error is produced.
echo "At least one or both of the variables BLACK_PROCESSES_LIST or WHITE_PROCESSES_LIST must be empty."
exit 1
elif [[ -n "$BLACK_PROCESSES_LIST" ]] ; then # If this variable is non-empty then set NEW_PIDS_COMMAND variable to bellow command
NEW_PIDS_COMMAND="top -b -n1 -c | grep -E '$BLACK_PROCESSES_LIST' | gawk '\$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
elif [[ -n "$WHITE_PROCESSES_LIST" ]] ; then # If this variable is non-empty then set NEW_PIDS_COMMAND variable to bellow command
NEW_PIDS_COMMAND="top -b -n1 -c | gawk 'NR>6' | grep -E -v '$WHITE_PROCESSES_LIST' | gawk '\$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
else
NEW_PIDS_COMMAND="top -b -n1 -c | gawk 'NR>6 && \$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
fi
# Search and limit violating PIDs
while sleep $DAEMON_INTERVAL
do
NEW_PIDS=$(eval "$NEW_PIDS_COMMAND") # Violating PIDs
LIMITED_PIDS=$(ps -eo args | gawk '$1=="cpulimit" {print $3}') # Already limited PIDs
QUEUE_PIDS=$(comm -23 <(echo "$NEW_PIDS" | sort -u) <(echo "$LIMITED_PIDS" | sort -u) | grep -v '^$') # PIDs in queue
for i in $QUEUE_PIDS
do
cpulimit -p $i -l $CPU_LIMIT -z & # Limit new violating processes
done
done3. CHANGE VARIABLES TO YOUR ENVIRONMENT NEEDS
CPU_LIMIT
Change this variable in above script if you would like to omit CPU consumption for every process to any other percentage then 20%. Please read "If using SMP computer" chapter bellow if you have SMP computer (more then 1 CPU or CPU with more then 1 core).
DAEMON_INTERVAL
Change this variable in above script if you would like to have more/less regular checking. Interval is in seconds and default is set to 3 seconds.
BLACK_PROCESS_LIST and WHITE_PROCESSES_LIST
Variable BLACK_PROCESSES_LIST limits only specified processes. If variable is empty (default) all violating processes are limited.
Variable WHITE_PROCESSES_LIST limits all processes except processes defined in this variable. If variable is empty (default) all violating processes are limited.
One or both of the variables BLACK_PROCESSES_LIST and WHITE_PROCESSES_LIST has to be empty - it is not logical that both variables are defined.
You can specify multiple processes in one of this two variables using delimiter characters "|" (without double quotes). Sample: if you would like to cpulimit all processes except mysql, firefox and gedit processes set variable: WHITE_PROCESSES_LIST="mysql|firefox|gedit"
4. PROCEDURE TO AUTOMATICALLY START DAEMON AT BOOT TIME
1. Set file permissions for root user:
Code:
sudo chmod 700 /usr/bin/cpulimit_daemon.shCode:
#!/bin/sh
#
# Script to start CPU limit daemon
#
set -e
case "$1" in
start)
if [ $(ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | wc -l) -eq 0 ]; then
nohup /usr/bin/cpulimit_daemon.sh >/dev/null 2>&1 &
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon started successfully"; else print " * cpulimit daemon can not be started" }'
else
echo " * cpulimit daemon can't be started, because it is already running"
fi
;;
stop)
CPULIMIT_DAEMON=$(ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | wc -l)
CPULIMIT_INSTANCE=$(ps -eo pid,args | gawk '$2=="cpulimit" {print $1}' | wc -l)
CPULIMIT_ALL=$((CPULIMIT_DAEMON + CPULIMIT_INSTANCE))
if [ $CPULIMIT_ALL -gt 0 ]; then
if [ $CPULIMIT_DAEMON -gt 0 ]; then
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | xargs kill -9 # kill cpulimit daemon
fi
if [ $CPULIMIT_INSTANCE -gt 0 ]; then
ps -eo pid,args | gawk '$2=="cpulimit" {print $1}' | xargs kill -9 # release cpulimited process to normal priority
fi
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon can not be stopped"; else print " * cpulimit daemon stopped successfully" }'
else
echo " * cpulimit daemon can't be stopped, because it is not running"
fi
;;
restart)
$0 stop
sleep 3
$0 start
;;
status)
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon is running"; else print " * cpulimit daemon is not running" }'
;;
esac
exit 0Code:
sudo chown root:root /etc/init.d/cpulimitCode:
sudo chmod 755 /etc/init.d/cpulimitCode:
sudo update-rc.d cpulimit defaultsCode:
sudo reboot5. MANUALLY CHECK, STOP, START AND RESTART DAEMON
Note: Daemon and service in this tutorial has equal meaning.
Note: For users using prior to Ubuntu 8.10 (like Ubuntu 8.04 LTS) instead of service command use "sudo /etc/init.d/cpulimit status/start/stop/restart" syntax or install sysvconfig package using command: sudo apt-get install sysvconfig
Check if cpulimit service is running
Check command returns: "cpulimit daemon is running" if service is running, or "cpulimit daemon is not running" if service is not running.
Code:
sudo service cpulimit statusYou can manually start cpulimit daemon which will start to omit CPU consumption.
Code:
sudo service cpulimit startStop command stops cpulimit daemon (so no new process will be limited) and also sets to all existing limited processes to have full access to CPU, just like it was before cpulimit was not running.
Code:
sudo service cpulimit stopIf you change some variables settings in /usr/bin/cpulimit_daemon.sh like CPU_LIMIT, DAEMON_INTERVAL, BLACK_PROCESSES_LIST or WHITE_PROCESSES_LIST, then after changing settings you must restart service.
Code:
sudo service cpulimit restart6. CHECK CPU CONSUMPTION WITH OR WITHOUT CPULIMIT DAEMON
Without daemon
1. stop cpulimit daemon (sudo service cpulimit stop)
2. execute CPU intensive tasks in background
3. execute command: top and check for %CPU column
Result of %CPU is probably more then 20% for each process.
With daemon turned on
1. start cpulimit daemon (sudo service cpulimit start)
2. execute the same CPU intensive tasks in background
3. execute command: top and check for %CPU column
Result of %CPU should be maximum 20% for each process.
Note: Don't forget at beginning %CPU can be more then 20%, because daemon has to catch violating process in interval of 3 seconds (set in script by default)
7. IF USING SMP COMPUTER
I have tested this code on Intel dual-core CPU computer - that behaves like SMP computer. Don't forget that top command and also cpulimit by default behaves in Irix mode, where 20% means 20% of one CPU. If there are two CPUs (or dual-core) then total %CPU can be 200%. In top command Irix mode can be turned off with command I (pressing <Shift>+i when top command is running) and Solaris mode is turned on, where total amount of CPU is divided by number of CPUs, so %CPU can be no more then 100% on any number of CPU computer. Please read more info about top command in top man page (search for I command). Please also read more about how cpulimit is operating on SMP computer in cpulimit official page.
But how does cpulimit daemon operates on SMP computer? Always in Irix mode. So if you would like to spend 20% of CPU power on 2-CPU computer then 40% should be used for CPU_LIMIT variable in cpulimit daemon script.
8. UNINSTALL CPULIMIT DAEMON AND CPULIMIT PROGRAM
If you would like to get rid of cpulimit daemon you can clean up your system by removing cpulimit daemon and uninstalling cpulimit program.
1. Stop cpulimit daemon
Code:
sudo service cpulimit stop # Stop cpulimit daemon and all cpulimited processesCode:
sudo update-rc.d -f cpulimit remove # Remove symbolic linksCode:
sudo rm /etc/init.d/cpulimit # Delete cpulimit boot-up scriptCode:
sudo rm /usr/bin/cpulimit_daemon.sh # Delete cpulimit daemon scriptCode:
sudo apt-get remove cpulimitIf you don't need this program for any other script, you can remote it.
Code:
sudo apt-get remove gawk9. NOTE ABOUT AUTHORS
I have just written daemon for cpulimit (bash scripts above). I am not the author of cpulimit project. If you need more info about cpulimit program, please read official cpulimit web page: http://cpulimit.sourceforge.net/.
Regards,
Abcuser
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