- 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 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
- -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) +
- -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
- -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
- -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>