CYCLICTEST(8) System Manager's Manual CYCLICTEST(8)

cyclictest - High resolution test program

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

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 processors 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 thread wakeups to a specific offset in microseconds
-b, --breaktrace=USEC
Send break trace command when latency > USEC
-c, --clock=CLOCK
select clock
0 = CLOCK_MONOTONIC (default)
1 = CLOCK_REALTIME
-d, --distance=DIST
Distance of thread intervals in us, default = 500
-D, --duration=TIME
Specify a length for the test run.
Append 'm', 'h', or 'd' to specify minutes, hours or days.
--latency=PM_Q0S
write PM_Q0S to /dev/cpu_dma_latency
-F, --fifo=<path>
Create a named pipe at path and write stats to it
-h, --histogram=US
Dump latency histogram to stdout after the run. US is the max latency time to be be tracked in microseconds. This option runs all threads at the same 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.
--histfile=<path>
Dump the latency histogram to <path> instead of stdout.
-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.
--json=FILENAME
Write final results into FILENAME, JSON formatted.
-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.
--laptop
Save battery when running cyclictest. This will give you poorer realtime results, but will not drain your battery so quickly.
--mainaffinity=CPUSET
Run the main thread on CPU #N. This only affects the main thread and not the measurement threads
-m, --mlockall
Lock current and future memory allocations to prevent being paged out
-M, --refresh_on_max
Delay updating the screen until a new max latency is hit. (useful for running cyclictest on low-bandwidth connections)
-N, --nsecs
Show results in nanoseconds instead of microseconds, which is the default unit.
-o, --oscope=RED
Oscilloscope mode, reduce verbose output by RED.
-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)
--policy=NAME
set the scheduler policy of the measurement threads where NAME is one of: other, normal, batch, idle, fifo, rr
--priospread
spread priority levels starting at a specified value
-q, --quiet
Print a summary only 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.
-R, --resolution
Check clock resolution, calling clock_gettime() many times. List of lock_gettime() values will be reported with -X
--secaligned [USEC]
align thread wakeups to the next full second and apply the optional offset.
-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.
-S, --smp
Set options for standard testing on SMP systems. Equivalent to using the options: "-t -a" as well keeping any specified priority equal across all threads
--spike=<trigger>
record all spikes > trigger
--spike-nodes=[num of nodes]
These are the maximum number of spikes we can record.
The default is 1024 if not specified.
--smi
Enable SMI count/detection on processors with SMI count support.
-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.
--tracemark
write a trace mark when -b latency is exceeded.
-u, --unbuffered
force unbuffered output for live processing
-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.

--dbg_cyclictest
Print info userful for debugging cyclictest
-x, --posix_timers
Use POSIX timers instead of clock_nanosleep.

numa(3), numactl(8),

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).
Updated by John Kacur <jkacur@redhat.com>

April 22, 2016