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

@node Top
@top niceload

@chapter NAME
@anchor{NAME}

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

@chapter SYNOPSIS
@anchor{SYNOPSIS}

@strong{niceload} [-v] [-h] [-n nice] [-I io] [-L load] [-M mem] [-N]
[-t time] [-s time|-f factor] ( command | -p PID )

@chapter DESCRIPTION
@anchor{DESCRIPTION}

GNU @strong{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 @strong{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, ...

@chapter OPTIONS
@anchor{OPTIONS}

@table @asis
@item @strong{-f} @emph{FACTOR}
@anchor{@strong{-f} @emph{FACTOR}}

@item @strong{--factor} @emph{FACTOR}
@anchor{@strong{--factor} @emph{FACTOR}}

Suspend time factor. Dynamically set @strong{-s} as amount over limit *
factor. Default is 1.

@item @strong{-H}
@anchor{@strong{-H}}

@item @strong{--hard}
@anchor{@strong{--hard}}

Hard limit. @strong{--hard} will suspend the process until the system is
under the limits. The default is @strong{--soft}.

@item @strong{--io} @emph{iolimit}
@anchor{@strong{--io} @emph{iolimit}}

@item @strong{-I} @emph{iolimit}
@anchor{@strong{-I} @emph{iolimit}}

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% satuated.

@strong{--io} will set both @strong{--start-io} and @strong{run-io}.

@item @strong{--load} @emph{loadlimit}
@anchor{@strong{--load} @emph{loadlimit}}

@item @strong{-L} @emph{loadlimit}
@anchor{@strong{-L} @emph{loadlimit}}

Limit for load average.

@strong{--load} will set both @strong{--start-load} and @strong{run-load}.

@item @strong{--mem} @emph{memlimit}
@anchor{@strong{--mem} @emph{memlimit}}

@item @strong{-M} @emph{memlimit}
@anchor{@strong{-M} @emph{memlimit}}

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

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

@strong{--mem} will set both @strong{--start-mem} and @strong{run-mem}.

@item @strong{--noswap}
@anchor{@strong{--noswap}}

@item @strong{-N}
@anchor{@strong{-N}}

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

@strong{--noswap} is over limit if the system is swapping both in and out.

@strong{--noswap} will set both @strong{--start-noswap} and @strong{run-noswap}.

@item @strong{-n} @emph{niceness}
@anchor{@strong{-n} @emph{niceness}}

@item @strong{--nice} @emph{niceness}
@anchor{@strong{--nice} @emph{niceness}}

Sets niceness. See @strong{nice}(1).

@item @strong{-p} @emph{PID}
@anchor{@strong{-p} @emph{PID}}

@item @strong{--pid} @emph{PID}
@anchor{@strong{--pid} @emph{PID}}

Process ID of process to suspend.

@item @strong{--quote}
@anchor{@strong{--quote}}

@item @strong{-q}
@anchor{@strong{-q}}

Quote the command line. Useful if the command contains chars like *,
$, >, and " that should not be interpreted by the shell.

@item @strong{--run-io} @emph{iolimit}
@anchor{@strong{--run-io} @emph{iolimit}}

@item @strong{--ri} @emph{iolimit}
@anchor{@strong{--ri} @emph{iolimit}}

@item @strong{--run-load} @emph{loadlimit}
@anchor{@strong{--run-load} @emph{loadlimit}}

@item @strong{--rl} @emph{loadlimit}
@anchor{@strong{--rl} @emph{loadlimit}}

@item @strong{--run-mem} @emph{memlimit}
@anchor{@strong{--run-mem} @emph{memlimit}}

@item @strong{--rm} @emph{memlimit}
@anchor{@strong{--rm} @emph{memlimit}}

Run limit. The running program will be slowed down if the system is
above the limit. See: @strong{--io}, @strong{--load}, @strong{--mem}, @strong{--noswap}.

@item @strong{--start-io} @emph{iolimit}
@anchor{@strong{--start-io} @emph{iolimit}}

@item @strong{--si} @emph{iolimit}
@anchor{@strong{--si} @emph{iolimit}}

@item @strong{--start-load} @emph{loadlimit}
@anchor{@strong{--start-load} @emph{loadlimit}}

@item @strong{--sl} @emph{loadlimit}
@anchor{@strong{--sl} @emph{loadlimit}}

@item @strong{--start-mem} @emph{memlimit}
@anchor{@strong{--start-mem} @emph{memlimit}}

@item @strong{--sm} @emph{memlimit}
@anchor{@strong{--sm} @emph{memlimit}}

Start limit. The program will not start until the system is below the
limit. See: @strong{--io}, @strong{--load}, @strong{--mem}, @strong{--noswap}.

@item @strong{--soft}
@anchor{@strong{--soft}}

@item @strong{-S}
@anchor{@strong{-S}}

Soft limit. @strong{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.

@item @strong{--suspend} @emph{SEC}
@anchor{@strong{--suspend} @emph{SEC}}

@item @strong{-s} @emph{SEC}
@anchor{@strong{-s} @emph{SEC}}

Suspend time. Suspend the command this many seconds when the max load
average is reached.

@item @strong{--recheck} @emph{SEC}
@anchor{@strong{--recheck} @emph{SEC}}

@item @strong{-t} @emph{SEC}
@anchor{@strong{-t} @emph{SEC}}

Recheck load time. Sleep SEC seconds before checking load
again. Default is 1 second.

@item @strong{--verbose}
@anchor{@strong{--verbose}}

@item @strong{-v}
@anchor{@strong{-v}}

Verbose. Print some extra output on what is happening. Use @strong{-v} until
you know what your are doing.

@end table

@chapter EXAMPLE: See niceload in action
@anchor{EXAMPLE: See niceload in action}

In terminal 1 run: top

In terminal 2 run:

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

@chapter EXAMPLE: Run updatedb
@anchor{EXAMPLE: Run updatedb}

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:

@strong{niceload -L 2 updatedb}

@chapter EXAMPLE: Run rsync
@anchor{EXAMPLE: Run rsync}

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:

@strong{niceload -L 3.4 -f 12 rsync -Ha /home/ /backup/home/}

@chapter EXAMPLE: Ensure enough disk cache
@anchor{EXAMPLE: Ensure enough disk cache}

Assume the program @strong{foo} uses 2 GB files intensively. @strong{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:

@strong{niceload --hard --run-mem 2g foo}

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

@chapter ENVIRONMENT VARIABLES
@anchor{ENVIRONMENT VARIABLES}

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

@chapter EXIT STATUS
@anchor{EXIT STATUS}

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

@chapter REPORTING BUGS
@anchor{REPORTING BUGS}

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

@chapter AUTHOR
@anchor{AUTHOR}

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 Ole Tange, http://ole.tange.dk and Free
Software Foundation, Inc.

@chapter LICENSE
@anchor{LICENSE}

Copyright (C) 2010 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.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

@section Documentation license I
@anchor{Documentation license I}

Permission is granted to copy, distribute and/or modify this documentation
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the file fdl.txt.

@section Documentation license II
@anchor{Documentation license II}

You are free:

@table @asis
@item @strong{to Share}
@anchor{@strong{to Share}}

to copy, distribute and transmit the work

@item @strong{to Remix}
@anchor{@strong{to Remix}}

to adapt the work

@end table

Under the following conditions:

@table @asis
@item @strong{Attribution}
@anchor{@strong{Attribution}}

You must attribute the work in the manner specified by the author or
licensor (but not in any way that suggests that they endorse you or
your use of the work).

@item @strong{Share Alike}
@anchor{@strong{Share Alike}}

If you alter, transform, or build upon this work, you may distribute
the resulting work only under the same, similar or a compatible
license.

@end table

With the understanding that:

@table @asis
@item @strong{Waiver}
@anchor{@strong{Waiver}}

Any of the above conditions can be waived if you get permission from
the copyright holder.

@item @strong{Public Domain}
@anchor{@strong{Public Domain}}

Where the work or any of its elements is in the public domain under
applicable law, that status is in no way affected by the license.

@item @strong{Other Rights}
@anchor{@strong{Other Rights}}

In no way are any of the following rights affected by the license:

@itemize
@item Your fair dealing or fair use rights, or other applicable
copyright exceptions and limitations;

@item The author's moral rights;

@item Rights other persons may have either in the work itself or in
how the work is used, such as publicity or privacy rights.

@end itemize

@end table

@table @asis
@item @strong{Notice}
@anchor{@strong{Notice}}

For any reuse or distribution, you must make clear to others the
license terms of this work.

@end table

A copy of the full license is included in the file as cc-by-sa.txt.

@chapter DEPENDENCIES
@anchor{DEPENDENCIES}

GNU @strong{niceload} uses Perl, and the Perl modules POSIX, and
Getopt::Long.

@chapter SEE ALSO
@anchor{SEE ALSO}

@strong{parallel}(1), @strong{nice}(1), @strong{uptime}(1)

@bye