ptsematest - 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]
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
- -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 <C.Emde@osadl.org>