NAME

       cpulimit -- limits the CPU usage of a process

SYNOPSIS

       cpulimit [TARGET] [OPTIONS...] [ -- PROGRAM]

DESCRIPTION

       TARGET must be exactly one of these:

       -p, --pid=N
              pid of the process

       -e, --exe=FILE
              name of the executable program file

       -P, --path=PATH
              absolute path name of the executable program file

       OPTIONS

       -b, --background
              run cpulimit in the background, freeing up the terminal

       -c, --cpu
              specify the number of CPU cores available. Usually this is detected for us.

       -l, --limit=N
              percentage  of  CPU  allowed  from  1  up.  Usually 1 - 100, but can be higher on multi-core CPUs.
              (mandatory)

       -k, --kill
              kill target process instead of throttling its CPU usage

       -r, --restore
              restore a process killed using the -k flag.

       -v, --verbose
              show control statistics

       -z, --lazy
              exit if there is no suitable target process, or if it dies

       --     This is the final CPUlimit option. All following options are for another program we will launch.

       -h, --help
              display this help and exit

EXAMPLES

       Assuming you have started `foo --bar` and you find out with top(1) or ps(1) that this  process  uses  all
       your CPU time you can either

       # cpulimit -e foo -l 50
              limits  the  CPU usage of the process by acting on the executable program file (note: the argument
              "--bar" is omitted)

       # cpulimit -p 1234 -l 50
              limits the CPU usage of the process by acting on its PID, as shown by ps(1)

       # cpulimit -P /usr/bin/foo -l 50
              same as -e but uses the absolute path name

       # /usr/bin/someapp

       # cpulimit -p $! -l 25 -b
              Useful for scripts where you want to throttle the last command run.

       # cpulimit -l 20 firefox
              Launch Firefox web browser and limit its CPU usage to 20%

       # cpulimit -l 25 -- firefox -private
              Launch Firefox web browser in private mode and limit its CPU usage to 25%

       # cpulimit -c 2 -p 12345 -l 25
              The -c flag sets the number of CPU cores  the  program  thinks  are  available.  Usually  this  is
              detected for us, but can be over-ridden.

       # cpulimit -l 20 -k firefox
              Launch the Firefox program and kill it if the process goes over 20% CPU usage.

NOTES

       •   cpulimit  always  sends  the  SIGSTOP  and  SIGCONT  signals to a process, both to verify that it can
           control it and to limit the average amount of  CPU  it  consumes.   This  can  result  in  misleading
           (annoying)  job  control  messages that indicate that the job has been stopped (when actually it was,
           but immediately restarted).  This can also cause  issues  with  interactive  shells  that  detect  or
           otherwise  depend  on  SIGSTOP/SIGCONT.   For example, you may place a job in the foreground, only to
           see    it    immediately    stopped    and    restarted    in    the    background.     (See     also
           <http://bugs.debian.org/558763>.)

       •   When  invoked  with the -e or -P options, cpulimit looks for any process under /proc with a name that
           matches the process name argument given.  Furthermore, it uses the  first  instance  of  the  process
           found.  To control a specific instance of a process, use the -p option and provide a PID.

       •   The current version of cpulimit assumes the kernel HZ value 100.

AUTHOR

       This manpage was written for the Debian project by gregor herrmann <gregoa@debian.org> but may be used by
       others.

cpulimit                                            June 2012                                        CPULIMIT(1)