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profil(2) [bsd man page]

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 bufsiz. After this call, the user's program counter (pc) is examined each clock tick (VAX and TAHOE: 100 ticks/second = 10 milliseconds per tick; 60 ticks/second ~= 16 milliseconds per tick); offset is sub- tracted 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 16 bits of fraction: 0xffff gives a 1-1 mapping of pc's to words in buff; 0x7fff maps each pair of instruction words together. 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 mem- ory fault. RETURN VALUE
A 0, indicating success, is always returned. SEE ALSO
gprof(1), prof(1), setitimer(2), monitor(3) 3rd Berkeley Distribution May 6, 1987 PROFIL(2)

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PROFIL(3)						     Linux Programmer's Manual							 PROFIL(3)

NAME
profil - execution time profile SYNOPSIS
#include <unistd.h> int profil(unsigned short *buf, size_t bufsiz, size_t offset, unsigned int scale); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): profil(): _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500) DESCRIPTION
This routine provides a means to find out in what areas your program spends most of its time. The argument buf points to bufsiz bytes of core. Every virtual 10 milliseconds, the user's program counter (PC) is examined: offset is subtracted and the result is multiplied by scale and divided by 65536. If the resulting value is less than bufsiz, then the corresponding entry in buf is incremented. If buf is NULL, profiling is disabled. RETURN VALUE
Zero is always returned. CONFORMING TO
Similar to a call in SVr4 (but not POSIX.1-2001). BUGS
profil() cannot be used on a program that also uses ITIMER_PROF interval timers (see setitimer(2)). True kernel profiling provides more accurate results. Libc 4.4 contained a kernel patch providing a system call profil. SEE ALSO
gprof(1), setitimer(2), sigaction(2), signal(2) COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2007-07-26 PROFIL(3)

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