pi_stress(8)						Linux System Administrator's Manual					      pi_stress(8)

NAME

       pi_stress - a stress test for POSIX Priority Inheritance mutexes

SYNOPSIS

       pi_stress  [-i|--inversions  inversions]  [-t|--duration  seconds]  [-g|--groups groups [-d|--debug] [-v|--verbose] [-s|--signal] [-r|--rr]
       [-p|--prompt] [-m|--mlockall] [-u|--uniprocessor]
       pi_stress -h|--help

DESCRIPTION

       pi_stress is a program used to stress the priority-inheritance code paths for POSIX mutexes, in both the Linux kernel and the C library. It
       runs  as  a  realtime-priority task and launches inversion machine thread groups. Each inversion group causes a priorty inversion condition
       that will deadlock if priority inheritance doesn't work.

OPTIONS

       -i n|--inversions=n
	      Run for n number of inversion conditions. This is the total number of inversions for all inversion groups. Default is -1	for  infi-
	      nite.

       -t n|--duration=n
	      Run the test for n seconds and then terminate.

       -g n|--groups=n
	      The number of inversion groups to run. Defaults to 10.

       -d|--debug
	      Run in debug mode; lots of extra prints

       -v|--verbose
	      Run with verbose messages

       -s|--signal
	      Terminate on receipt of SIGTERM (Ctrl-C). Default is to terminate on any keypress.

       -r|--rr
	      Run inversion group threads as SCHED_RR (round-robin). The default is to run the inversion threads as SCHED_FIFO.

       -p|--prompt
	      Prompt before actually starting the stress test

       -u|--uniprocessor
	      Run  all threads on one processor. The default is to run all inversion group threads on one processor and the admin threads (report-
	      ing thread, keyboard reader, etc.) on a different processor.

       -m|--mlockall
	      Call mlockall to lock current and future memory allocations and prevent being paged out

       -h|--help
	      Display a short help message and options.

CAVEATS

       The pi_stress test threads run as SCHED_FIFO or SCHED_RR threads, which means that they can starve critical system threads. It is advisable
       to  change the scheduling policy of critical system threads to be SCHED_FIFO prior to running pi_stress and use a priority of 10 or higher,
       to prevent those threads from being starved by the stress test.

BUGS

       No documented bugs.

AUTHOR

       Clark Williams <williams@redhat.com>

								   Nov 27, 2006 						      pi_stress(8)