loadwatch - run a program when machine is idle

loadwatch [options] -p pid | [--] prog [args]

loadwatch either spawns a child process prog with the arguments args and controls it with all its process group, or takes control of an already running process with pid pid with all its process group.

loadwatch allows the controlled processes to run while the load average remains below high_limit. Every delay seconds, loadwatch checks the load average. If the load is above high_limit, the child is suspended; the child is resumed when the load falls below low_limit.

A summary of options is included below.

-h high_limit

A decimal value that sets the system load at which the child process will be suspended. (Default: 1.25)

-l low_limit

A decimal value that sets the system load at which the child process will be resumed. (Default: 0.25)

-d delay

An integral number of seconds that sets how often the system load will be checked. (Default: 10)

-n copies

An integer value that sets the number of copies of prog to run. (Default: 1)

-u file

Create a UNIX domain socket file for use by lw-ctl.

-p pid

The pid of the program that should be controlled by loadwatch (with all its process group).

lw-ctl(1), nice(1)

You should choose low_limit and high_limit carefully. When the load drops below low_limit, the process(es) will be resumed, and it should not, by itself, cause the load to raise above high_limit, or the whole will oscillate, periodically suspending and resuming the process(es).

Similarly, if several instances of loadwatch are running, they may resume their processes at the same time, leading to oscillations if the limits are not carefully chosen. Hence, each instance of loadwatch affects every other instance on the computer, and should not be considered in isolation.

This manual page was written by Dale E. Martin <dmartin@debian.org>, for the Debian GNU/Linux system (but may be used by others). It was then updated by Nicolas Boullis <nboullis@debian.org>.