PROFIL

Section: System Calls (2)
Updated: 27 January 1988
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NAME

profil - execution time profile

SYNOPSIS

profil(buff, bufsiz, offset, scale)
char *buff;
int bufsiz, offset, scale;

DESCRIPTION

profil() enables run-time execution profiling, and reserves a buffer for maintaining raw profiling statistics. buff points to an area of core of length bufsiz (in bytes). After the call to profil, the user's program counter (pc) is examined at each clock tick (10 milliseconds on Sun-4 systems, 20 milliseconds on Sun-2 and Sun-3 systems); offset is subtracted from its value, and the result multiplied by scale. If the resulting number corresponds to a word within the buffer, that word is incremented.

scale is interpreted as an unsigned, fixed-point fraction with binary point at the left: 0x10000 gives a 1-to-1 mapping of pc values to words in buff; 0x8000 maps each pair of instruction words together. 0x2 maps all instructions onto the beginning of buff (producing a non-interrupting core clock).

Profiling is turned off by giving a scale of 0 or 1. It is rendered ineffective by giving a bufsiz of 0. Profiling is turned off when an execve() is executed, but remains on in child and parent both after a fork(). Profiling is turned off if an update in buff would cause a memory fault.

RETURN VALUE

A 0, indicating success, is always returned.