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
8
10 sigwaittest [-a|--affinity PROC] [-b|--breaktrace USEC] [-d|--distance
11 DIST] [-D|--duration TIME] [-f|--fork [OPT]] [-i|--interval INTV]
12 [--json FILENAME] [-l|--loops LOOPS] [-p|--prio PRIO] [-t|--threads
13 [NUM]]
14
16 The program sigwaittest starts two threads or, optionally, forks two
17 processes that are synchronized via signals and measures the latency
18 between sending a signal and returning from sigwait().
19
21 -a, --affinity[=PROC]
22 Run on processor number PROC. If PROC is not specified, run on
23 current processor.
24 -b, --breaktrace=USEC
26 Send break trace command when latency > USEC. This is a debug‐
27 ging option to control the latency tracer in the realtime pre‐
28 emption patch. It is useful to track down unexpected large la‐
29 tencies of a system.
30 -d, --distance=DIST
32 Set the distance of thread intervals in microseconds (default is
33 500 us). When cyclictest is called with the -t option and more
34 than one thread is created, then this distance value is added to
35 the interval of the threads: Interval(thread N) = Inter‐
36 val(thread N-1) + DIST
37 -D, --duration=TIME
39 Specify a length for the test run.
40 Append 'm', 'h', or 'd' to specify minutes, hours or days.
41 -f, --fork[=OPT]
43 Instead of creating threads (which is the default), fork new
44 processes
45 -i, --interval=INTV
47 Set the base interval of the thread(s) in microseconds (default
48 is 1000 us). This sets the interval of the first thread. See
49 also -d.
50 --json=FILENAME
52 Write final results into FILENAME, JSON formatted.
53 -l, --loops=LOOPS
55 Set the number of loops. The default is 0 (endless). This option
56 is useful for automated tests with a given number of test cy‐
57 cles. sigwaittest is stopped once the number of timer intervals
58 has been reached.
59 -p, --prio=PRIO
61 Set the priority of the process.
62 -t, --threads[=NUM]
64 Set the number of test threads (default is 1, if this option is
65 not given). If NUM is specified, create NUM test threads. If NUM
66 is not specified, NUM is set to the number of available CPUs.
67
69 The following example was running on a 4-way CPU:
70 # sigwaittest -a -t -p99 -i100 -d25 -l1000000
72 #0: ID11510, P99, CPU0, I100; #1: ID11511, P99, CPU0, Cycles 1000000
73 #2: ID11512, P98, CPU1, I125; #3: ID11513, P98, CPU1, Cycles 817484
74 #4: ID11514, P97, CPU2, I150; #5: ID11515, P97, CPU2, Cycles 668213
75 #6: ID11516, P96, CPU3, I175; #7: ID11517, P96, CPU3, Cycles 597344
76 #1 -> #0, Min 1, Cur 2, Avg 3, Max 30
77 #3 -> #2, Min 1, Cur 26, Avg 3, Max 42
78 #5 -> #4, Min 1, Cur 46, Avg 4, Max 67
79 #7 -> #6, Min 1, Cur 2, Avg 3, Max 74
80
82 Carsten Emde <C.Emde@osadl.org>
83
85 kill(2), sigwait(3)
86 0.1 sigwaittest(8)