NAME

       pi_stress - a stress test for POSIX Priority Inheritance mutexes

SYNOPSIS

       pi_stress  [-d|--debug]  [-D|--duration  [-g|--groups  N]  [-i|--inversions  INV]  [--json
       FILENAME]  [-m|--mlockall]  [-p|--prompt]   [-q|--quiet]   [-r|--rr]   [-s|--sched   OPTS]
       [-u|--uniprocessor] [-v|--verbose] [-V|--version]

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

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

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

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

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

       -i N|--inversions=N
              N number of inversion conditions. This is the total number of  inversions  for  all
              inversion groups. Default is -1 for infinite.

       --json=FILENAME
              Write final results into FILENAME , JSON formatted.

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

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

       -q|--quiet
              Suppress running output

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

       -s OPTS|--sched OPTS
              scheduling options per thread type:
              id=[high|med|low],
              policy=[fifo,rr],priority=N,
              policy=deadline,runtime=N,deadline=N,period=N

       -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.

       -v|--verbose
              Run with verbose messages

       -V|--version
              Print version number

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)