NAME
svsematest - Start two threads or fork two processes and measure the
latency of SYSV semaphores
SYNTAX
svsematest [-a|-a PROC] [-b USEC] [-d DIST] [-f] [-i INTV] [-l loops]
[-p PRIO] [-t|-t NUM]
DESCRIPTION
The program svsematest starts two threads or, optionally, forks two
processes that are synchronized via SYSV semaphores and measures the
latency between releasing a semaphore on one side and getting it on the
other side.
OPTIONS
-a, --affinity[=PROC]
Run on procesor 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 cylictest 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
-f, --fork
Instead of creating threads (which is the default), fork new
processes
-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. svsematest 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 specifed, NUM is set to the number of available CPUs.
EXAMPLES
The following example was running on a 4-way CPU:
# svsematest -a -t -p99 -i100 -d25 -l1000000
#0: ID13110, P99, CPU0, I100; #1: ID13111, P99, CPU0, Cycles 1000000
#2: ID13112, P98, CPU1, I125; #3: ID13113, P98, CPU1, Cycles 813573
#4: ID13114, P97, CPU2, I150; #5: ID13115, P97, CPU2, Cycles 667285
#6: ID13116, P96, CPU3, I175; #7: ID13117, P96, CPU3, Cycles 591403
#1 -> #0, Min 1, Cur 2, Avg 2, Max 12
#3 -> #2, Min 1, Cur 3, Avg 2, Max 12
#5 -> #4, Min 1, Cur 3, Avg 3, Max 12
#7 -> #6, Min 1, Cur 2, Avg 3, Max 11
AUTHORS
Carsten Emde <C.Emde@osadl.org>
SEE ALSO
semop(2)
0.1 svsematest(8)