hackbench(8)															      hackbench(8)

NAME

       hackbench - scheduler benchmark/stress test

SYNOPSIS

       hackbench  [-p|--pipe]  [-s|--datasize  <bytes>]  [-l|--loops  <num-loops>]  [-g|--groups <num-groups>] [-f|--fds <num-fds>] [-T|--threads]
       [-P|--process] [--help]

DESCRIPTION

       Hackbench is both a benchmark and a stress test for the Linux kernel scheduler. It's main job is to create a specified number of  pairs	of
       schedulable entities (either threads or traditional processes) which communicate via either sockets or pipes and time how long it takes for
       each pair to send data back and forth.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with two dashes ("--").
       A summary of options is included below.

       -p, --pipe
	      Sends the data via a pipe instead of the socket (default)

       -s, --datasize=<size in bytes>
	      Sets the amount of data to send in each message

       -l, --loops=<number of loops>
	      How many messages each sender/receiver pair should send

       -g, --groups=<number of groups>
	      Defines how many groups of senders and receivers should be started

       -f, --fds=<number of file descriptors>
	      Defines how many file descriptors each child should use.	Note that the effective number will be twice the amount you set  here,	as
	      the sender and receiver children will each open the given amount of file descriptors.

       -T, --threads
	      Each sender/receiver child will be a POSIX thread of the parent.

       -P, --process
	      Hackbench will use fork() on all children (default behaviour)

       --help
	      Shows a simple help screen

EXAMPLES

       Running hackbench without any options will give default behaviour, using fork() and sending data between senders and receivers via sockets.

       user@host: ~ $ hackbench
       Running in process mode with 10 groups using 40 file descriptors each (== 400 tasks)
       Each sender will pass 100 messages of 100 bytes
       Time: 0.890

       To use pipes between senders and receivers and using threads instead of fork(), run

       user@host: ~ $ hackbench --pipe --threads   (or hackbench -p -T)
       Running in threaded mode with 10 groups using 40 file descriptors each (== 400 tasks)
       Each sender will pass 100 messages of 100 bytes
       Time: 0.497

       Set  the datasize to 512 bytes, do 200 messages per sender/receiver pairs and use 15 groups using 25 file descriptors per child, in process
       mode.

       user@host: ~ $ hackbench -s 512 -l 200 -g 15 -f 25 -P
       Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
       Each sender will pass 200 messages of 512 bytes
       Time: 4.497

AUTHORS

       hackbench was written by Rusty Russell <rusty@rustcorp.com.au> with contributions from Yanmin  Zhang  <yanmin_zhang@linux.intel.com>,  Ingo
       Molnar <mingo@elte.hu> and David Sommerseth <davids@redhat.com>

       This manual page was written by Clark Williams <williams@redhat.com> and David Sommerseth <davids@redhat.com>

HISTORY

       This  version  of  hackbench  is  based on the code downloaded from http://people.redhat.com/mingo/cfs-scheduler/tools/hackbench.c.  Yanmin
       Zhang merged the original hackbench code from
       http://devresources.linuxfoundation.org/craiger/hackbench/src/hackbench.c which uses fork() and a modified version from
       http://www.bullopensource.org/posix/pi-futex/hackbench_pth.c which uses pthread only and gave the possibility to change	behaviour  at  run
       time.   Hackbench  have	since then gone through some more rewriting to improve error handling and proper tracking of fork()ed children, to
       avoid leaving zombies on the system if hackbench stops unexpectedly.

								February  23, 2010						      hackbench(8)