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@(#)profil.2 5.1 (Berkeley) 05/09/85

C 4 profil - execution time profile

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

Buff points to an area of core whose length (in bytes) is given by bufsiz . After this call, the user's program counter (pc) is examined each clock tick (10 milliseconds); offset is subtracted from it, and the result multiplied by scale . If the resulting number corresponds to a word inside buff, that word is incremented.

The scale is interpreted as an unsigned, fixed-point fraction with binary point at the left: 0x10000 gives a 1-1 mapping of pc's 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.

A 0, indicating success, is always returned. gprof(1), setitimer(2), monitor(3)