profil(2) System Calls Manual profil(2) Name profil - execution time profile Syntax void profil(buff, bufsiz, offset, scale) char *buff; int bufsiz, offset, scale; Description The 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 exam- ined each clock tick (on RISC machines, 4 milliseconds; on VAX machines, 10 milliseconds); offset is subtracted from the pc, and the result is 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 program counter'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 both child and parent after a fork. Profiling is turned off if an update in buff would cause a mem- ory fault. See Also gprof(1) (for VAX only), setitimer(2), monitor(3) profil(2)