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31 .\" @(#)profil.2 8.1 (Berkeley) 6/4/93
32 .\" $FreeBSD: src/lib/libc/sys/profil.2,v 1.9.2.3 2001/12/14 18:34:01 ru Exp $
39 .Nd control process profiling
45 .Fn profil "char *samples" "size_t size" "unsigned long offset" "unsigned int scale"
49 function enables or disables
50 program counter profiling of the current process.
51 If profiling is enabled,
52 then at every profiling clock tick,
53 the kernel updates an appropriate count in the
56 The frequency of the profiling clock is recorded
57 in the header in the profiling output file.
63 bytes and is divided into
64 a series of 16-bit bins.
65 Each bin counts the number of times the program counter
66 was in a particular address range in the process
67 when a profiling clock tick occurred while profiling was enabled.
68 For a given program counter address,
69 the number of the corresponding bin is given
71 .Bd -literal -offset indent
72 [(pc - offset) / 2] * scale / 65536
77 parameter is the lowest address at which
78 the kernel takes program counter samples.
81 parameter ranges from 1 to 65536 and
82 can be used to change the span of the bins.
83 A scale of 65536 maps each bin to 2 bytes of address range;
84 a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on.
85 Intermediate values provide approximate intermediate ranges.
88 value of 0 disables profiling.
92 .Bl -tag -width /usr/lib/gcrt0.o -compact
93 .It Pa /usr/lib/gcrt0.o
94 profiling C run-time startup file
96 conventional name for profiling output file
99 The following error may be reported:
104 contains an invalid address.
111 function call appeared in
114 This routine should be named
119 argument should really be a vector of type
120 .Fa "unsigned short" .
122 The format of the gmon.out file is undocumented.