1sigwaittest(8) sigwaittest(8)
2
6 sigwaittest - Start two threads or fork two processes and measure the
7 latency between sending and receiving a signal
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10 sigwaittest [-a|-a PROC] [-b USEC] [-d DIST] [-f] [-i INTV] [-l loops]
11 [-p PRIO] [-t|-t NUM]
12
14 The program sigwaittest starts two threads or, optionally, forks two
15 processes that are synchronized via signals and measures the latency
16 between sending a signal and returning from sigwait().
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19 -a, --affinity[=PROC]
20 Run on processor number PROC. If PROC is not specified, run on
21 current processor.
22 -b, --breaktrace=USEC
24 Send break trace command when latency > USEC. This is a debug‐
25 ging option to control the latency tracer in the realtime pre‐
26 emption patch. It is useful to track down unexpected large
27 latencies of a system.
28 -d, --distance=DIST
30 Set the distance of thread intervals in microseconds (default is
31 500 us). When cyclictest is called with the -t option and more
32 than one thread is created, then this distance value is added to
33 the interval of the threads: Interval(thread N) = Inter‐
34 val(thread N-1) + DIST
35 -D, --duration=TIME
37 Specify a length for the test run.
38 Append 'm', 'h', or 'd' to specify minutes, hours or days.
39 -f, --fork
41 Instead of creating threads (which is the default), fork new
42 processes
43 -i, --interval=INTV
45 Set the base interval of the thread(s) in microseconds (default
46 is 1000 us). This sets the interval of the first thread. See
47 also -d.
48 -l, --loops=LOOPS
50 Set the number of loops. The default is 0 (endless). This option
51 is useful for automated tests with a given number of test
52 cycles. sigwaittest is stopped once the number of timer inter‐
53 vals has been reached.
54 -p, --prio=PRIO
56 Set the priority of the process.
57 -t, --threads[=NUM]
59 Set the number of test threads (default is 1, if this option is
60 not given). If NUM is specified, create NUM test threads. If NUM
61 is not specified, NUM is set to the number of available CPUs.
62
64 The following example was running on a 4-way CPU:
65 # sigwaittest -a -t -p99 -i100 -d25 -l1000000
67 #0: ID11510, P99, CPU0, I100; #1: ID11511, P99, CPU0, Cycles 1000000
68 #2: ID11512, P98, CPU1, I125; #3: ID11513, P98, CPU1, Cycles 817484
69 #4: ID11514, P97, CPU2, I150; #5: ID11515, P97, CPU2, Cycles 668213
70 #6: ID11516, P96, CPU3, I175; #7: ID11517, P96, CPU3, Cycles 597344
71 #1 -> #0, Min 1, Cur 2, Avg 3, Max 30
72 #3 -> #2, Min 1, Cur 26, Avg 3, Max 42
73 #5 -> #4, Min 1, Cur 46, Avg 4, Max 67
74 #7 -> #6, Min 1, Cur 2, Avg 3, Max 74
75
77 Carsten Emde <C.Emde@osadl.org>
78
80 kill(2), sigwait(3)
81 0.1 sigwaittest(8)