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  priority  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 infinite.

       -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

       -D, --duration=TIME
              Specify a length for the test run.
              Append 'm', 'h', or 'd' to specify minutes, hours or days.

       -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  (reporting  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)