1pmqtest(8) pmqtest(8)
2# SPDX-License-Identifier: GPL-2.0-or-later
6
8 pmqtest - Start pairs of threads and measure the latency of interpro‐
9 cess communication with POSIX messages queues
10
12 pmqtest [-a|-a PROC] [-b USEC] [-d DIST] [-D TIME] [-f TO] [-h] [-i
13 INTV] [--json FILENAME] [-l LOOPS] [-p PRIO] [-q] [-S] [-t|-t NUM]
14
16 The program pmqtest starts pairs of threads that are synchronized via
17 mq_send/mw_receive() and measures the latency between sending and re‐
18 ceiving the message.
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 pmqtest is called with the -t option and more than
34 one thread is created, then this distance value is added to the
35 interval of the threads: Interval(thread N) = Interval(thread
36 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 -h, --help
43 Print help message
44 -f, --forcetimeout=TO
46 Set an artificial delay of the send function to force timeout of
47 the receiver, requires the -T option
48 -i, --interval=INTV
50 Set the base interval of the thread(s) in microseconds (default
51 is 1000 us). This sets the interval of the first thread. See
52 also -d.
53 --json=FILENAME
55 Write final results into FILENAME, JSON formatted.
56 -l, --loops=LOOPS
58 Set the number of loops. The default is 0 (endless). This option
59 is useful for automated tests with a given number of test cy‐
60 cles. pmqtest is stopped once the number of timer intervals has
61 been reached.
62 -p, --prio=PRIO
64 Set the priority of the process.
65 -q, --quiet
67 Print a summary only on exit. Useful for automated tests, where
68 only the summary output needs to be captured.
69 -S, --smp
71 Test mode for symmetric multi-processing, implies -a and -t and
72 uses the same priority on all threads.
73 -t, --threads[=NUM]
75 Set the number of test threads (default is 1, if this option is
76 not given). If NUM is specified, create NUM test threads. If NUM
77 is not specified, NUM is set to the number of available CPUs.
78 -T, --timeout=TO
80 Use mq_timedreceive() instead of mq_receive() and specify time‐
81 out TO in seconds.
82
84 The following example was running on an 8-way processor:
85 # pmqtest -Sp99 -i100 -d0
87 #0: ID10047, P99, CPU0, I100; #1: ID10048, P99, CPU0, Cycles 153695
88 #2: ID10049, P99, CPU1, I100; #3: ID10050, P99, CPU1, Cycles 154211
89 #4: ID10051, P99, CPU2, I100; #5: ID10052, P99, CPU2, Cycles 156823
90 #6: ID10053, P99, CPU3, I100; #7: ID10054, P99, CPU3, Cycles 158202
91 #8: ID10055, P99, CPU4, I100; #9: ID10056, P99, CPU4, Cycles 153399
92 #10: ID10057, P99, CPU5, I100; #11: ID10058, P99, CPU5, Cycles 153992
93 #12: ID10059, P99, CPU6, I100; #13: ID10060, P99, CPU6, Cycles 156576
94 #14: ID10061, P99, CPU7, I100; #15: ID10062, P99, CPU7, Cycles 157957
95 #1 -> #0, Min 1, Cur 8, Avg 5, Max 18
96 #3 -> #2, Min 1, Cur 4, Avg 5, Max 18
97 #5 -> #4, Min 1, Cur 5, Avg 5, Max 19
98 #7 -> #6, Min 1, Cur 4, Avg 4, Max 17
99 #9 -> #8, Min 1, Cur 9, Avg 5, Max 18
100 #11 -> #10, Min 1, Cur 8, Avg 5, Max 18
101 #13 -> #12, Min 1, Cur 4, Avg 5, Max 29
102 #15 -> #14, Min 1, Cur 8, Avg 4, Max 17
103
105 Carsten Emde <C.Emde@osadl.org>
106
108 mq_send(3p), mq_receive(3p)
109 0.1 pmqtest(8)