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31 .\" @(#)profil.2 8.1 (Berkeley) 6/4/93
38 .Nd control process profiling
44 .Fn profil "char *samples" "size_t size" "vm_offset_t offset" "int scale"
48 system call enables or disables
49 program counter profiling of the current process.
50 If profiling is enabled,
51 then at every profiling clock tick,
52 the kernel updates an appropriate count in the
55 The frequency of the profiling clock is recorded
56 in the header in the profiling output file.
62 bytes and is divided into
63 a series of 16-bit bins.
64 Each bin counts the number of times the program counter
65 was in a particular address range in the process
66 when a profiling clock tick occurred while profiling was enabled.
67 For a given program counter address,
68 the number of the corresponding bin is given
70 .Bd -literal -offset indent
71 [(pc - offset) / 2] * scale / 65536
76 argument is the lowest address at which
77 the kernel takes program counter samples.
80 argument ranges from 1 to 65536 and
81 can be used to change the span of the bins.
82 A scale of 65536 maps each bin to 2 bytes of address range;
83 a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on.
84 Intermediate values provide approximate intermediate ranges.
87 value of 0 disables profiling.
91 .Bl -tag -width /usr/lib/gcrt0.o -compact
92 .It Pa /usr/lib/gcrt0.o
93 profiling C run-time startup file
95 conventional name for profiling output file
98 The following error may be reported:
103 contains an invalid address.
110 functionality first appeared in
113 This routine should be named
118 argument should really be a vector of type
119 .Fa "unsigned short" .
121 The format of the gmon.out file is undocumented.