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>