sigwaittest - Start two threads or fork two processes and measure the
latency between sending and receiving a signal
sigwaittest [-a|-a PROC] [-b USEC] [-d DIST] [-f] [-i INTV] [-l loops]
[-p PRIO] [-t|-t NUM]
The program sigwaittest starts two threads or, optionally, forks two
processes that are synchonized via signals and measures the latency
between sending a signal and returning from sigwait().
Run on procesor number PROC. If PROC is not specified, run on
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.
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
Instead of creating threads (which is the default), fork new
Set the base interval of the thread(s) in microseconds (default
is 1000 us). This sets the interval of the first thread. See
Set the number of loops. The default is 0 (endless). This option
is useful for automated tests with a given number of test
cycles. sigwaittest is stopped once the number of timer
intervals has been reached.
Set the priority of the process.
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.
The following example was running on a 4-way CPU:
# sigwaittest -a -t -p99 -i100 -d25 -l1000000
#0: ID11510, P99, CPU0, I100; #1: ID11511, P99, CPU0, Cycles 1000000
#2: ID11512, P98, CPU1, I125; #3: ID11513, P98, CPU1, Cycles 817484
#4: ID11514, P97, CPU2, I150; #5: ID11515, P97, CPU2, Cycles 668213
#6: ID11516, P96, CPU3, I175; #7: ID11517, P96, CPU3, Cycles 597344
#1 -> #0, Min 1, Cur 2, Avg 3, Max 30
#3 -> #2, Min 1, Cur 26, Avg 3, Max 42
#5 -> #4, Min 1, Cur 46, Avg 4, Max 67
#7 -> #6, Min 1, Cur 2, Avg 3, Max 74
Carsten Emde <C.Emde@osadl.org>