Ubuntu Manpage: cyclictest - High resolution test program

Provided by: rt-tests_0.87-1ubuntu1_amd64

NAME

       cyclictest - High resolution test program

SYNOPSIS

       cyclictest  [  -hfmnqrsvMS ] [-a proc ] [-A align ] [-b usec ] [-c clock ] [-d dist ] [-h histogram ] [-i
       intv ] [-l loop ] [-o red ] [-p prio ] [-t num ] [-D time] [-w] [-W] [-y policy ] [ -S | -U ]

OPTIONS

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

-a, --affinity[=PROC-SET]
Run threads on the set of procesors given by PROC-SET. If PROC-SET is not specified, all
processors will be used. Threads will be assigned to processors in the set in numeric order, in a
round-robin fashion.
The set of processors can be specified as A,B,C, or A-C, or A-B,D-F, and so on*. The ! character
can be used to negate a set. For example, !B-D means to use all available CPUs except B through
D. The cpu numbers are the same as shown in the processor field in /proc/cpuinfo. See numa(3)
for more information on specifying CPU sets. * Support for CPU sets requires libnuma version >=
2. For libnuma v1, PROC-SET, if specified, must be a single CPU number.

-A, --align=USEC
Align measurement thread wakeups to a specific offset in microseconds

-b, --breaktrace=USEC
Send break trace command when latency > USEC. This is a debugging option to control the latency
tracer in the realtime preemption patch. It is useful to track down unexpected large latencies on
a system. This option does only work with following kernel config options.

For kernel < 2.6.24:
* CONFIG_PREEMPT_RT=y
* CONFIG_WAKEUP_TIMING=y
* CONFIG_LATENCY_TRACE=y
* CONFIG_CRITICAL_PREEMPT_TIMING=y
* CONFIG_CRITICAL_IRQSOFF_TIMING=y

For kernel >= 2.6.24:
* CONFIG_PREEMPT_RT=y
* CONFIG_FTRACE
* CONFIG_IRQSOFF_TRACER=y
* CONFIG_PREEMPT_TRACER=y
* CONFIG_SCHED_TRACER=y
* CONFIG_WAKEUP_LATENCY_HIST

kernel configuration options enabled. The USEC parameter to the -b option defines a maximum
latency value, which is compared against the actual latencies of the test. Once the measured
latency is higher than the given maximum, the kernel tracer and cyclictest is stopped. The trace
can be read from /proc/latency_trace. Please be aware that the tracer adds significant overhead to
the kernel, so the latencies will be much higher than on a kernel with latency tracing disabled.

-c, --clock=CLOCK
Selects the clock, which is used:

* 0 selects CLOCK_MONOTONIC, which is the monotonic increasing system time (default).
* 1 selects CLOCK_REALTIME, which is the time of day time.

CLOCK_REALTIME can be set by settimeofday, while CLOCK_MONOTONIC can not be modified by the user.
This option has no influence when the -s option is given.

-C, --context
context switch tracing (used with -b)

-d, --distance=DIST
Set the distance of thread intervals in microseconds (default is 500us). When cyclictest is called
with the -t option and more than one thread is created, then this distance value is added to the
interval of the threads: Interval(thread N) = Interval(thread N-1) + DIST

-E, --event
event tracing (used with -b)

-f, --ftrace
Enable function tracing using ftrace as tracer. This option is available only with -b.

-h, --histogram=MAXLATENCYINUS
Dump latency histogram to stdout. US means the max time to be be tracked in microseconds. When you
use -h option to get histogram data, Cyclictest runs many threads with same priority without
priority--.

-H, --histofall=MAXLATENCYINUS
Same as -h except that an additional histogram column is displayed at the right that contains
summary data of all thread histograms. If cyclictest runs a single thread only, the -H option is
equivalent to -h.

-i, --interval=INTV
Set the base interval of the thread(s) in microseconds (default is 1000us). This sets the interval
of the first thread. See also -d.

-l, --loops=LOOPS
Set the number of loops. The default is 0 (endless). This option is useful for automated tests
with a given number of test cycles. Cyclictest is stopped once the number of timer intervals has
been reached.

-n, --nanosleep
Use clock_nanosleep instead of posix interval timers. Setting this option runs the tests with
clock_nanosleep instead of posix interval timers.

-N, --nsecs
Show results in nanoseconds instead of microseconds, which is the default unit.

-o, --oscope=RED
Oscilloscope mode, reduce verbose output by RED.

-O, --traceopt=TRACING_OPTION
Used to pass tracing options to ftrace tracers. May be invoked mutiple times for multiple trace
options. For example trace options look at /sys/kernel/debug/tracing/trace_options

-p, --prio=PRIO
Set the priority of the first thread. The given priority is set to the first test thread. Each
further thread gets a lower priority: Priority(Thread N) = max(Priority(Thread N-1) - 1, 0)

-q, --quiet
Run the tests quiet and print only a summary on exit. Useful for automated tests, where only the
summary output needs to be captured.

-r, --relative
Use relative timers instead of absolute. The default behaviour of the tests is to use absolute
timers. This option is there for completeness and should not be used for reproducible tests.

-s, --system
Use sys_nanosleep and sys_setitimer instead of posix timers. Note, that -s can only be used with
one thread because itimers are per process and not per thread. -s in combination with -n uses the
nanosleep syscall and is not restricted to one thread.

-T, --tracer=TRACEFUNC
set the ftrace tracer function. Used with the -b option. Must be one of the trace functions
available from <debugfs-mountpoint>/kernel/debug/tracing/available_tracers

-t, --threads[=NUM]
Set the number of test threads (default is 1). Create NUM test threads. If NUM is not specified,
NUM is set to the number of available CPUs. See -d, -i and -p for further information.

-m, --mlockall
Lock current and future memory allocations to prevent being paged out

-v, --verbose
Output values on stdout for statistics. This option is used to gather statistical information
about the latency distribution. The output is sent to stdout. The output format is:

n:c:v

where n=task number c=count v=latency value in us. Use this option in combination with -l

-D, --duration=TIME
Run the test for the specified time, which defaults to seconds. Append 'm', 'h', or 'd' to specify
minutes, hours or days

-w, --wakeup
task wakeup tracing (used with -b)

-W, --wakeuprt
rt-task wakeup tracing (used with -b)

-y, --policy=NAME
set the scheduler policy of the measurement threads where NAME is one of: other, normal, batch,
idle, fifo, rr

-M, --refresh_on_max
delay updating the screen until a new max latency is hit (useful for running cyclictest on low-
bandwidth connections)

-S, --smp
Set options for standard testing on SMP systems. Equivalent to using the options: "-t -a -n" as
well keeping any specified priority equal across all threads

-U, --numa
Similar to the above --smp option, this implies the "-t -a -n" options, as well as a constant
measurement interval, but also forces memory allocations using the numa(3) policy library. Thread
stacks and data structures are allocated from the NUMA node local to the core to which the thread
is bound. Requires the underlying kernel to have NUMA support compiled in.

AUTHOR

       cyclictest was written by Thomas Gleixner <tglx@linuxtronix.de>.

       This manual page was written by Alessio Igor Bogani <abogani@texware.it>, for the Debian project (but may
       be used by others).

                                               december  20, 2007                                  CYCLICTEST(8)

NAME

SYNOPSIS

OPTIONS

SEE ALSO

AUTHOR