xref: /freebsd/lib/libc/gmon/moncontrol.3 (revision dc36d6f9bb1753f3808552f3afd30eda9a7b206a)
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28.Dd June 14, 2004
29.Dt MONCONTROL 3
30.Os
31.Sh NAME
32.Nm moncontrol ,
33.Nm monstartup
34.Nd control execution profile
35.Sh LIBRARY
36.Lb libc
37.Sh SYNOPSIS
38.In sys/types.h
39.In sys/gmon.h
40.Ft void
41.Fn moncontrol "int mode"
42.Ft void
43.Fn monstartup "u_long lowpc" "u_long highpc"
44.Sh DESCRIPTION
45An executable program compiled using the
46.Fl pg
47option to
48.Xr cc 1
49automatically includes calls to collect statistics for the
50.Xr gprof 1
51call-graph execution profiler.
52In typical operation, profiling begins at program startup
53and ends when the program calls exit.
54When the program exits, the profiling data are written to the file
55.Ar progname Ns Pa .gmon ,
56where progname is the name of the program, then
57.Xr gprof 1
58can be used to examine the results.
59.Pp
60The
61.Fn moncontrol
62function
63selectively controls profiling within a program.
64When the program starts, profiling begins.
65To stop the collection of histogram ticks and call counts use
66.Fn moncontrol 0 ;
67to resume the collection of histogram ticks and call counts use
68.Fn moncontrol 1 .
69This feature allows the cost of particular operations to be measured.
70Note that an output file will be produced on program exit
71regardless of the state of
72.Fn moncontrol .
73.Pp
74Programs that are not loaded with
75.Fl pg
76may selectively collect profiling statistics by calling
77.Fn monstartup
78with the range of addresses to be profiled.
79The
80.Fa lowpc
81and
82.Fa highpc
83arguments
84specify the address range that is to be sampled;
85the lowest address sampled is that of
86.Fa lowpc
87and the highest is just below
88.Fa highpc .
89Only functions in that range that have been compiled with the
90.Fl pg
91option to
92.Xr cc 1
93will appear in the call graph part of the output;
94however, all functions in that address range will
95have their execution time measured.
96Profiling begins on return from
97.Fn monstartup .
98.Sh ENVIRONMENT
99The following environment variables affect the execution of
100.Nm :
101.Bl -tag -width ".Ev PROFIL_USE_PID"
102.It PROFIL_USE_PID
103If set, the pid of the process is inserted into the filename.
104.El
105.Sh FILES
106.Bl -tag -width progname.gmon -compact
107.It Pa progname.gmon
108execution data file
109.El
110.Sh SEE ALSO
111.Xr cc 1 ,
112.Xr gprof 1 ,
113.Xr profil 2 ,
114.Xr clocks 7
115