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 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

       -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 specified, 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)