ptsematest(8) Start two threads and measure the latency of interprocess communication with POSIX mutex.


ptsematest [-a|-a PROC] [-b USEC] [-d DIST] [-i INTV] [-l loops] [-p PRIO] [-t|-t NUM]


The program ptsematest starts two threads that are synchronized via pthread_mutex_unlock()/pthread_mutex_lock() and measures the latency between releasing and getting the lock.


-a, --affinity[=PROC]
Run on processor number PROC. If PROC is not specified, run on current processor.
-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 of a system.
-d, --distance=DIST
Set the distance of thread intervals in microseconds (default is 500 us). 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
-i, --interval=INTV
Set the base interval of the thread(s) in microseconds (default is 1000 us). 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. ptsematest is stopped once the number of timer intervals has been reached.
-p, --prio=PRIO
Set the priority of the process.
-t, --threads[=NUM]
Set the number of test threads (default is 1, if this option is not given). If NUM is specified, create NUM test threads. If NUM is not specified, NUM is set to the number of available CPUs.


The following example was running on a 4-way processor:

# ptsematest -a -t -p99 -i100 -d25 -l1000000
#0: ID8672, P99, CPU0, I100; #1: ID8673, P99, CPU0, Cycles 1000000
#2: ID8674, P98, CPU1, I125; #3: ID8675, P98, CPU1, Cycles 811035
#4: ID8676, P97, CPU2, I150; #5: ID8677, P97, CPU2, Cycles 668130
#6: ID8678, P96, CPU3, I175; #7: ID8679, P96, CPU3, Cycles 589423
#1 -> #0, Min    1, Cur    1, Avg    2, Max   11
#3 -> #2, Min    1, Cur    2, Avg    2, Max   13
#5 -> #4, Min    1, Cur    4, Avg    3, Max   12
#7 -> #6, Min    1, Cur    4, Avg    2, Max   12


Carsten Emde <[email protected]>