DOKK / manpages / debian 10 / parallel / niceload.1.en
NICELOAD(1) parallel NICELOAD(1)

niceload - slow down a program when the load average is above a certain limit

niceload [-v] [-h] [-n nice] [-I io] [-L load] [-M mem] [-N] [--sensor program] [-t time] [-s time|-f factor] ( command | -p PID [-p PID ...] | --prg program )

GNU niceload will slow down a program when the load average (or other system activity) is above a certain limit. When the limit is reached the program will be suspended for some time. Then resumed again for some time. Then the load average is checked again and we start over.

Instead of load average niceload can also look at disk I/O, amount of free memory, or swapping activity.

If the load is 3.00 then the default settings will run a program like this:

run 1 second, suspend (3.00-1.00) seconds, run 1 second, suspend (3.00-1.00) seconds, run 1 second, ...

Suspend if the system is running on battery. Shorthand for: -l -1 --sensor 'cat /sys/class/power_supply/BAT0/status /proc/acpi/battery/BAT0/state 2>/dev/null |grep -i -q discharging; echo $?'
Suspend time factor. Dynamically set -s as amount over limit * factor. Default is 1.
Hard limit. --hard will suspend the process until the system is under the limits. The default is --soft.
Limit for I/O. The amount of disk I/O will be computed as a value 0 - 10, where 0 is no I/O and 10 is at least one disk is 100% saturated.

--io will set both --start-io and run-io.

Limit for load average.

--load will set both --start-load and run-load.

Limit for free memory. This is the amount of bytes available as free + cache. This limit is treated opposite other limits: If the system is above the limit the program will run, if it is below the limit the program will stop

memlimit can be postfixed with K, M, G, T, or P which would multiply the size with 1024, 1048576, 1073741824, or 1099511627776 respectively.

--mem will set both --start-mem and run-mem.

No swapping. If the system is swapping both in and out it is a good indication that the system is memory stressed.

--noswap is over limit if the system is swapping both in and out.

--noswap will set both --start-noswap and run-noswap.

Shorthand for --nethops 3.
Network nice. Pause if the internet connection is overloaded.

niceload finds a router h hops closer to the internet. It pings this every second. If the latency is more than 50% bigger than the median, it is regarded as being over the limit.

--nethops can be combined with --hard. Without --hard the program may be able to queue up so much traffic that it will take longer than the --suspend time to clear it. --hard is useful for traffic that does not break by being suspended for a longer time.

--nethops can be combined with a high --suspend. This way a program can be allowed to do a bit of traffic now and then. This is useful to keep the connection alive.

Sets niceness. See nice(1).
Process ID of process to suspend. You can specify multiple process IDs with multiple -p PID.
Name of running program to suspend. You can specify multiple programs with multiple --prg program. If no processes with the name program is found, niceload with search for substrings containing program.
Quote the command line. Useful if the command contains chars like *, $, >, and " that should not be interpreted by the shell.
Run limit. The running program will be slowed down if the system is above the limit. See: --io, --load, --mem, --noswap.
Read sensor. Use sensor program to read a sensor.

This will keep the CPU temperature below 80 deg C on GNU/Linux:

  niceload -l 80000 -f 0.001 --sensor 'sort -n /sys/devices/platform/coretemp*/temp*_input' gzip *

This will stop if the disk space < 100000.

  niceload -H -l -100000 --sensor "df . | awk '{ print \$4 }'" echo
Start limit. The program will not start until the system is below the limit. See: --io, --load, --mem, --noswap.
Soft limit. niceload will suspend a process for a while and then let it run for a second thus only slowing down a process while the system is over one of the given limits. This is the default.
Suspend time. Suspend the command this many seconds when the max load average is reached.
Recheck load time. Sleep SEC seconds before checking load again. Default is 1 second.
Verbose. Print some extra output on what is happening. Use -v until you know what your are doing.

In terminal 1 run: top

In terminal 2 run:

niceload -q perl -e '$|=1;do{$l==$r or print "."; $l=$r}until(($r=time-$^T)>50)'

This will print a '.' every second for 50 seconds and eat a lot of CPU. When the load rises to 1.0 the process is suspended.

Running updatedb can often starve the system for disk I/O and thus result in a high load.

Run updatedb but suspend updatedb if the load is above 2.00:

niceload -L 2 updatedb

rsync can just like updatedb starve the system for disk I/O and thus result in a high load.

Run rsync but keep load below 3.4. If load reaches 7 sleep for (7-3.4)*12 seconds:

niceload -L 3.4 -f 12 rsync -Ha /home/ /backup/home/

Assume the program foo uses 2 GB files intensively. foo will run fast if the files are in disk cache and be slow as a crawl if they are not in the cache.

To ensure 2 GB are reserved for disk cache run:

niceload --hard --run-mem 2g foo

This will not guarantee that the 2 GB memory will be used for the files for foo, but it will stop foo if the memory for disk cache is too low.

None. In future versions $NICELOAD will be able to contain default settings.

Exit status should be the same as the command being run (untested).

Report bugs to <bug-parallel@gnu.org>.

Copyright (C) 2004-11-19 Ole Tange, http://ole.tange.dk

Copyright (C) 2005,2006,2006,2008,2009,2010 Ole Tange, http://ole.tange.dk

Copyright (C) 2010,2011,2012 Ole Tange, http://ole.tange.dk and Free Software Foundation, Inc.

Copyright (C) 2010,2011,2012 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or at your option any later version.

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GNU niceload uses Perl, and the Perl modules POSIX, and Getopt::Long.

parallel(1), nice(1), uptime(1)

2018-12-01 20161222