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Thread: HOWTO: Set maximum CPU consumption in percentage by any process

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    HOWTO: Set maximum CPU consumption in percentage by any process

    EDIT: Tutorial updated on September 15, 2011. New features added to scripts and some bugs fixed.
    EDIT: 'Attention' info added for properly specifying the variables on January 14, 2014.

    Purpose of cpulimit daemon:
    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 cpulimit
    2. Install gawk package.
    Code:
    sudo apt-get install gawk

    2. 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
    done

    3. 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"

    Attention: Make sure you don't put any spaces in variable, for example WHITE_PROCESS_LIST= "mysql|firefox|gedit" (notice space character after = character) is not going to work correctly. You need to specify the variable without spaces: WHITE_PROCESS_LIST="mysql|firefox|gedit"

    4. PROCEDURE TO AUTOMATICALLY START DAEMON AT BOOT TIME

    1. Set file permissions for root user:
    Code:
    sudo chmod 755 /usr/bin/cpulimit_daemon.sh
    2. Open text editor with root privileges and save bellow script to new file /etc/init.d/cpulimit
    Code:
    #!/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 0
    3. Change file's owner to root:
    Code:
    sudo chown root:root /etc/init.d/cpulimit
    4. Change permissions:
    Code:
    sudo chmod 755 /etc/init.d/cpulimit
    5. Add script to boot-up procedure directories:
    Code:
    sudo update-rc.d cpulimit defaults
    6. Reboot to check if script starts cpulimit daemon at boot time:
    Code:
    sudo reboot

    5. 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 status
    Start cpulimit service
    You can manually start cpulimit daemon which will start to omit CPU consumption.
    Code:
    sudo service cpulimit start
    Stop cpulimit service
    Stop 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 stop
    Restart cpulimit service
    If 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 restart

    6. 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 processes
    2. Remove daemon from boot-up procedure
    Code:
    sudo update-rc.d -f cpulimit remove    # Remove symbolic links
    3. Delete boot-up procedure
    Code:
    sudo rm /etc/init.d/cpulimit           # Delete cpulimit boot-up script
    4. Delete cpulimit daemon
    Code:
    sudo rm /usr/bin/cpulimit_daemon.sh    # Delete cpulimit daemon script
    5. Uninstall cpulimit program
    Code:
    sudo apt-get remove cpulimit
    6. Uninstall gawk program
    If you don't need this program for any other script, you can remote it.
    Code:
    sudo apt-get remove gawk

    9. 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
    Last edited by abcuser; January 14th, 2014 at 08:35 AM.

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