profil(3) [posix man page]
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(): Since glibc 2.21: _DEFAULT_SOURCE In glibc 2.19 and 2.20: _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500) Up to and including glibc 2.19: _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. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +----------+---------------+-----------+ |Interface | Attribute | Value | +----------+---------------+-----------+ |profil() | Thread safety | MT-Unsafe | +----------+---------------+-----------+ CONFORMING TO
Similar to a call in SVr4 (but not POSIX.1). 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), sprof(1), setitimer(2), sigaction(2), signal(2) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2017-09-15 PROFIL(3)
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PROFIL(2) BSD System Calls Manual PROFIL(2) NAME
profil -- control process profiling LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <unistd.h> int profil(char *samples, size_t size, vm_offset_t offset, int scale); DESCRIPTION
The profil() system call enables or disables program counter profiling of the current process. If profiling is enabled, then at every pro- filing clock tick, the kernel updates an appropriate count in the samples buffer. The frequency of the profiling clock is recorded in the header in the profiling output file. The buffer samples contains size bytes and is divided into a series of 16-bit bins. Each bin counts the number of times the program counter was in a particular address range in the process when a profiling clock tick occurred while profiling was enabled. For a given program counter address, the number of the corresponding bin is given by the relation: [(pc - offset) / 2] * scale / 65536 The offset argument is the lowest address at which the kernel takes program counter samples. The scale argument ranges from 1 to 65536 and can be used to change the span of the bins. A scale of 65536 maps each bin to 2 bytes of address range; a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. Intermediate values provide approximate intermediate ranges. A scale value of 0 disables profiling. RETURN VALUES
The profil() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. FILES
/usr/lib/gcrt0.o profiling C run-time startup file gmon.out conventional name for profiling output file ERRORS
The following error may be reported: [EFAULT] The buffer samples contains an invalid address. SEE ALSO
gprof(1) HISTORY
The profil() function appeared in Version 7 AT&T UNIX. BUGS
This routine should be named profile(). The samples argument should really be a vector of type unsigned short. The format of the gmon.out file is undocumented. BSD
June 4, 1993 BSD