profil - control process profiling
profil(char *samples, size_t size, u_long offset, u_int
The profil() function enables or disables program counter
the current process. If profiling is enabled, then at every
the kernel updates an appropriate count in the samples
The buffer samples contains size bytes and is divided into a
16-bit bins. Each bin counts the number of times the program counter was
in a particular address range in the process when a clock
while profiling was enabled. For a given program counter
number of the corresponding bin is given by the relation:
[(pc - offset) / 2] * scale / 65536
The offset parameter is the lowest address at which the kernel takes program
counter samples. The scale parameter ranges from 1 to
65536 and can
be used to change the span of the bins. A scale of 65536
maps each bin
to 2 bytes of address range; a scale of 32768 gives 4 bytes,
8 bytes and so on. Intermediate values provide approximate
ranges. A scale value of 0 disables profiling.
If the scale value is nonzero and the buffer samples contains an illegal
address, profil() returns -1, profiling is terminated, and
errno is set
appropriately. Otherwise, profil() returns 0.
/usr/lib/gcrt0.o profiling C run-time startup file
gmon.out conventional name for profiling output
The following error may be reported:
[EFAULT] The buffer samples contains an invalid address.
This routine should be named profile().
The samples argument should really be a vector of type
The format of the gmon.out file is undocumented.
OpenBSD 3.6 June 4, 1993
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