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cpulimit -- limits the CPU usage of a process
cpulimit [TARGET] [OPTIONS...] [ -- PROGRAM]
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
- -b, --background
- run cpulimit in the background, freeing up the terminal
- -f, --foreground
- run cpulimit in foreground while waiting for launched process to
- -c, --cpu
- specify the number of CPU cores available. Usually this is detected for
- -l, --limit=N
- percentage of CPU allowed from 1 up. Usually 1 - 100, but can be higher on
multi-core CPUs. (mandatory)
- -q, --quiet
- Runs in quiet mode, avoids writing update messages to console.
- -k, --kill
- kill target process instead of throttling its CPU usage
- -m, --monitor-forks
- watch and throttle child processes of the target process Warning: It is
usually a bad idea to use this flag on a shell script. The commands in the
script will each spawn a process which will, in turn, spawn more copies of
this program to throttle them, bogging down the system.
- -r, --restore
- restore a process killed using the -k flag.
- -s, --signal
- send an alternative signal to the watched process when we exit. Default is
- -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
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
- # 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
- # 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
- # cpulimit -l 20 -p 1234 -s SIGTERM
- Throttle process 1234 at 20% CPU usage. If cpulimit is forced to exit, it
sends the watched process the SIGTERM signal.
- 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
- 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.
This manpage was written for the Debian project by gregor herrmann
<email@example.com> but may be used by others.