1ptsematest(8) ptsematest(8)
2# SPDX-License-Identifier: GPL-2.0-or-later
6
8 ptsematest - Start two threads and measure the latency of interprocess
9 communication with POSIX mutex.
10
12 ptsematest [-a|--affinity [PROC]] [-b|--breaktrace USEC] [-d|--distance
13 DIST] [-D|--duration TIME] [-h|--help] [-i|--interval INTV] [--json
14 FILENAME] [-l|--loops LOOPS] [-p|--prio PRIO] [-q|--quiet] [-S|--smp]
15 [-t|--threads [NUM]]
16
18 The program ptsematest starts two threads that are synchronized via
19 pthread_mutex_unlock()/pthread_mutex_lock() and measures the latency
20 between releasing and getting the lock.
21
23 -a, --affinity[=PROC]
24 Run on processor number PROC. If PROC is not specified, run on
25 current processor.
26 -b, --breaktrace=USEC
28 Send break trace command when latency > USEC. This is a debug‐
29 ging option to control the latency tracer in the realtime pre‐
30 emption patch. It is useful to track down unexpected large la‐
31 tencies of a system.
32 -d, --distance=DIST
34 Set the distance of thread intervals in microseconds (default is
35 500 us). When cyclictest is called with the -t option and more
36 than one thread is created, then this distance value is added to
37 the interval of the threads: Interval(thread N) = Inter‐
38 val(thread N-1) + DIST
39 -D, --duration=TIME
41 Specify a length for the test run.
42 Append 'm', 'h', or 'd' to specify minutes, hours or days.
43 -h, --help
45 Print help message.
46 -i, --interval=INTV
48 Set the base interval of the thread(s) in microseconds (default
49 is 1000 us). This sets the interval of the first thread. See
50 also -d.
51 --json=FILENAME
53 Write final results into FILENAME, JSON formatted.
54 -l, --loops=LOOPS
56 Set the number of loops. The default is 0 (endless). This option
57 is useful for automated tests with a given number of test cy‐
58 cles. ptsematest is stopped once the number of timer intervals
59 has been reached.
60 -p, --prio=PRIO
62 Set the priority of the process.
63 -q, --quiet
65 Print a summary only on exit. Useful for automated tests, where
66 only the summary output needs to be captured.
67 -S, --smp
69 SMP testing: options -a -t and same priority
70 -t, --threads[=NUM]
72 Set the number of test threads (default is 1, if this option is
73 not given). If NUM is specified, create NUM test threads. If NUM
74 is not specified, NUM is set to the number of available CPUs.
75
77 The following example was running on a 4-way processor:
78 # ptsematest -a -t -p99 -i100 -d25 -l1000000
80 #0: ID8672, P99, CPU0, I100; #1: ID8673, P99, CPU0, Cycles 1000000
81 #2: ID8674, P98, CPU1, I125; #3: ID8675, P98, CPU1, Cycles 811035
82 #4: ID8676, P97, CPU2, I150; #5: ID8677, P97, CPU2, Cycles 668130
83 #6: ID8678, P96, CPU3, I175; #7: ID8679, P96, CPU3, Cycles 589423
84 #1 -> #0, Min 1, Cur 1, Avg 2, Max 11
85 #3 -> #2, Min 1, Cur 2, Avg 2, Max 13
86 #5 -> #4, Min 1, Cur 4, Avg 3, Max 12
87 #7 -> #6, Min 1, Cur 4, Avg 2, Max 12
88
90 Carsten Emde <C.Emde@osadl.org>
91
93 pthread_mutex_lock(3p), pthread_mutex_unlock(3p)
94 0.1 ptsematest(8)