1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Donn Seeley of BSDI. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)profil.2 8.1 (Berkeley) 6/4/93 36.\" $FreeBSD: src/lib/libc/sys/profil.2,v 1.9.2.3 2001/12/14 18:34:01 ru Exp $ 37.\" 38.Dd June 4, 1993 39.Dt PROFIL 2 40.Os 41.Sh NAME 42.Nm profil 43.Nd control process profiling 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In unistd.h 48.Ft int 49.Fn profil "char *samples" "size_t size" "vm_offset_t offset" "int scale" 50.Sh DESCRIPTION 51The 52.Fn profil 53function enables or disables 54program counter profiling of the current process. 55If profiling is enabled, 56then at every profiling clock tick, 57the kernel updates an appropriate count in the 58.Fa samples 59buffer. 60The frequency of the profiling clock is recorded 61in the header in the profiling output file. 62.Pp 63The buffer 64.Fa samples 65contains 66.Fa size 67bytes and is divided into 68a series of 16-bit bins. 69Each bin counts the number of times the program counter 70was in a particular address range in the process 71when a profiling clock tick occurred while profiling was enabled. 72For a given program counter address, 73the number of the corresponding bin is given 74by the relation: 75.Bd -literal -offset indent 76[(pc - offset) / 2] * scale / 65536 77.Ed 78.Pp 79The 80.Fa offset 81parameter is the lowest address at which 82the kernel takes program counter samples. 83The 84.Fa scale 85parameter ranges from 1 to 65536 and 86can be used to change the span of the bins. 87A scale of 65536 maps each bin to 2 bytes of address range; 88a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. 89Intermediate values provide approximate intermediate ranges. 90A 91.Fa scale 92value of 0 disables profiling. 93.Sh RETURN VALUES 94.Rv -std profil 95.Sh FILES 96.Bl -tag -width /usr/lib/gcrt0.o -compact 97.It Pa /usr/lib/gcrt0.o 98profiling C run-time startup file 99.It Pa gmon.out 100conventional name for profiling output file 101.El 102.Sh ERRORS 103The following error may be reported: 104.Bl -tag -width Er 105.It Bq Er EFAULT 106The buffer 107.Fa samples 108contains an invalid address. 109.El 110.Sh SEE ALSO 111.Xr gprof 1 112.Sh HISTORY 113A 114.Fn profil 115function call appeared in 116.At v7 . 117.Sh BUGS 118This routine should be named 119.Fn profile . 120.Pp 121The 122.Fa samples 123argument should really be a vector of type 124.Fa "unsigned short" . 125.Pp 126The format of the gmon.out file is undocumented. 127