NAME¶
cpulimit -- limits the CPU usage of a process
SYNOPSIS¶
cpulimit [TARGET] [
OPTIONS...]
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)
- -v, --verbose
- show control statistics
- -z, --lazy
- exit if there is no suitable target process, or if it
dies
- -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 -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.
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.
