xref: /openbsd/lib/libc/gmon/moncontrol.3 (revision 771fbea0)
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30.Dd $Mdocdate: May 7 2016 $
31.Dt MONCONTROL 3
32.Os
33.Sh NAME
34.Nm moncontrol ,
35.Nm monstartup
36.Nd control execution profile
37.Sh SYNOPSIS
38.In sys/gmon.h
39.Ft void
40.Fn moncontrol "int mode"
41.Ft void
42.Fn monstartup "u_long lowpc" "u_long highpc"
43.Sh DESCRIPTION
44An executable program compiled using the
45.Fl pg
46option to
47.Xr cc 1
48automatically includes calls to collect statistics for the
49.Xr gprof 1
50call-graph execution profiler.
51In typical operation, profiling begins at program startup
52and ends when the program calls exit.
53When the program exits, the profiling data are written to the file
54.Em gmon.out ,
55then
56.Xr gprof 1
57can be used to examine the results.
58.Pp
59.Fn moncontrol
60selectively controls profiling within a program.
61When the program starts, profiling begins.
62To stop the collection of histogram ticks and call counts use
63.Fn moncontrol 0 ;
64to resume the collection of histogram ticks and call counts use
65.Fn moncontrol 1 .
66This feature allows the cost of particular operations to be measured.
67Note that an output file will be produced on program exit
68regardless of the state of
69.Fn moncontrol .
70.Pp
71Programs that are not loaded with
72.Fl pg
73may selectively collect profiling statistics by calling
74.Fn monstartup
75with the range of addresses to be profiled.
76.Fa lowpc
77and
78.Fa highpc
79specify the address range that is to be sampled;
80the lowest address sampled is that of
81.Fa lowpc
82and the highest is just below
83.Fa highpc .
84Only functions in that range that have been compiled with the
85.Fl pg
86option to
87.Xr cc 1
88will appear in the call graph part of the output;
89however, all functions in that address range will
90have their execution time measured.
91Profiling begins on return from
92.Fn monstartup .
93.Sh FILES
94.Bl -tag -width gmon.out -compact
95.It Pa gmon.out
96execution data file
97.El
98.Sh SEE ALSO
99.Xr cc 1 ,
100.Xr gprof 1 ,
101.Xr profil 2
102