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)
