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35 .\" @(#)profil.2 8.1 (Berkeley) 6/4/93
36 .\" $FreeBSD: src/lib/libc/sys/profil.2,v 1.9.2.3 2001/12/14 18:34:01 ru Exp $
43 .Nd control process profiling
49 .Fn profil "char *samples" "size_t size" "vm_offset_t offset" "int scale"
53 function enables or disables
54 program counter profiling of the current process.
55 If profiling is enabled,
56 then at every profiling clock tick,
57 the kernel updates an appropriate count in the
60 The frequency of the profiling clock is recorded
61 in the header in the profiling output file.
67 bytes and is divided into
68 a series of 16-bit bins.
69 Each bin counts the number of times the program counter
70 was in a particular address range in the process
71 when a profiling clock tick occurred while profiling was enabled.
72 For a given program counter address,
73 the number of the corresponding bin is given
75 .Bd -literal -offset indent
76 [(pc - offset) / 2] * scale / 65536
81 parameter is the lowest address at which
82 the kernel takes program counter samples.
85 parameter ranges from 1 to 65536 and
86 can be used to change the span of the bins.
87 A scale of 65536 maps each bin to 2 bytes of address range;
88 a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on.
89 Intermediate values provide approximate intermediate ranges.
92 value of 0 disables profiling.
96 .Bl -tag -width /usr/lib/gcrt0.o -compact
97 .It Pa /usr/lib/gcrt0.o
98 profiling C run-time startup file
100 conventional name for profiling output file
103 The following error may be reported:
108 contains an invalid address.
115 function call appeared in
118 This routine should be named
123 argument should really be a vector of type
124 .Fa "unsigned short" .
126 The format of the gmon.out file is undocumented.