PROFIL(2) | System Calls Manual | PROFIL(2) |
profil
—
#include <unistd.h>
int
profil
(char
*samples, size_t
size, unsigned long
offset, unsigned int
scale);
profil
() function enables or disables program
counter profiling of the current process. If profiling is enabled, then at
every clock tick, the kernel updates an appropriate count in the
samples buffer.
The buffer samples contains size bytes and is divided into a series of 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 tick occurred while profiling was enabled. For a given program counter address, the 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, 16384 gives 8 bytes and so on. Intermediate values provide approximate intermediate ranges. A scale value of 0 disables profiling.
profil
() returns -1, profiling is terminated and
errno is set appropriately. Otherwise
profil
() returns 0.
EFAULT
]profile
().
The samples argument should really be a vector of type unsigned short.
The format of the gmon.out file is undocumented.
June 4, 1993 | NetBSD 9.2 |