term% cat index.txt PROFIL(2) System Calls Manual PROFIL(2)
NAME
profil - execution time profile
SYNOPSIS
profil(buff, bufsiz, offset, scale)
char *buff;
int bufsiz, offset, scale;
DESCRIPTION
Buff points to an area of core whose length (in bytes) is given by buf‐
siz. After this call, the user's program counter (pc) is examined each
clock tick (60th second); offset is subtracted from it, and the result
multiplied by scale. If the resulting number corresponds to a word in‐
side buff, that word is incremented.
The scale is interpreted as an unsigned, fixed-point fraction with bi‐
nary point at the left: 0177777(8) gives a 1-1 mapping of pc's to words
in buff; 077777(8) maps each pair of instruction words together. 02(8)
maps all instructions onto the beginning of buff (producing a non-in‐
terrupting 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
exec is executed, but remains on in child and parent both after a fork.
Profiling may be turned off if an update in buff would cause a memory
fault.
SEE ALSO
monitor(3), prof(1)
BUGS
Profiling does not work for interpreters; if a signal were given to a
process when its cpu-time clock ticked then profiling interpreters
would be possible.
PROFIL(2)