cyclictest - High resolution test program
cyclictest [ -hfmnqrsvMS ] [-a proc ] [-b usec ] [-c clock ] [-d dist ]
[-h histogram ] [-i intv ] [-l loop ] [-o red ] [-p prio ] [-t num ]
[-D time] [-w] [-W] [-y policy]
These programs follow the usual GNU command line syntax, with long
options starting with two dashes (’--’).
A summary of options is included below.
Run all threads on procesor number PROC. If PROC is not
specified, run thread #N on processor #N.
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:
For kernel >= 2.6.24:
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.
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.
context switch tracing (used with -b)
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
event tracing (used with -b)
Enable function tracing using ftrace as tracer. This option is
available only with -b.
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
Set the base interval of the thread(s) in microseconds (default
is 1000us). This sets the interval of the first thread. See also
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.
Use clock_nanosleep instead of posix interval timers. Setting
this option runs the tests with clock_nanosleep instead of posix
Show results in nanoseconds instead of microseconds, which is
the default unit.
Oscilloscope mode, reduce verbose output by RED.
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
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)
Run the tests quiet and print only a summary on exit. Useful for
automated tests, where only the summary output needs to be
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.
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.
set the ftrace tracer function. Used with the -b option. Must be
one of the trace functions available from <debugfs-
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.
Lock current and future memory allocations to prevent being
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:
where n=task number c=count v=latency value in us. Use this
option in combination with -l
Run the test for the specified time, which defaults to seconds.
Append ’m’, ’h’, or ’d’ to specify minutes, hours or days
task wakeup tracing (used with -b)
rt-task wakeup tracing (used with -b)
set the scheduler policy of the measurement threads where NAME
is one of: other, normal, batch, idle, fifo, rr
delay updating the screen until a new max latency is hit (useful
for running cyclictest on low-bandwidth connections)
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
cyclictest was written by Thomas Gleixner <firstname.lastname@example.org>.
This manual page was written by Alessio Igor Bogani
<email@example.com>, for the Debian project (but may be used by
december 20, 2007