1svsematest(8) svsematest(8)
2
6 svsematest - Start two threads or fork two processes and measure the
7 latency of SYSV semaphores
8
10 svsematest [-a|--affinity NUM] [-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] [-q|--quiet]
13 [-S|--smp] [-t|--threads [NUM]]
14
16 The program svsematest starts two threads or, optionally, forks two
17 processes that are synchronized via SYSV semaphores and measures the
18 latency between releasing a semaphore on one side and getting it on the
19 other side.
20
22 -a, --affinity[=NUM]
23 Run on processor number NUM. If PROC is not specified, run on
24 current processor.
25 -b, --breaktrace=USEC
27 Send break trace command when latency > USEC. This is a debug‐
28 ging option to control the latency tracer in the realtime pre‐
29 emption patch. It is useful to track down unexpected large la‐
30 tencies of a system.
31 -d, --distance=DIST
33 Set the distance of thread intervals in microseconds (default is
34 500 us). When cyclictest is called with the -t option and more
35 than one thread is created, then this distance value is added to
36 the interval of the threads: Interval(thread N) = Inter‐
37 val(thread N-1) + DIST
38 -D, --duration=TIME
40 Specify a length for the test run.
41 Append 'm', 'h', or 'd' to specify minutes, hours or days.
42 -f, --fork
44 Instead of creating threads (which is the default), fork new
45 processes
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. svsematest 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 of all threads
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 CPU:
78 # svsematest -a -t -p99 -i100 -d25 -l1000000
80 #0: ID13110, P99, CPU0, I100; #1: ID13111, P99, CPU0, Cycles 1000000
81 #2: ID13112, P98, CPU1, I125; #3: ID13113, P98, CPU1, Cycles 813573
82 #4: ID13114, P97, CPU2, I150; #5: ID13115, P97, CPU2, Cycles 667285
83 #6: ID13116, P96, CPU3, I175; #7: ID13117, P96, CPU3, Cycles 591403
84 #1 -> #0, Min 1, Cur 2, Avg 2, Max 12
85 #3 -> #2, Min 1, Cur 3, Avg 2, Max 12
86 #5 -> #4, Min 1, Cur 3, Avg 3, Max 12
87 #7 -> #6, Min 1, Cur 2, Avg 3, Max 11
88
90 Carsten Emde <C.Emde@osadl.org>
91
93 semop(2)
94 0.1 svsematest(8)