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. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)profil.2 8.1 (Berkeley) 6/4/93 32.\" $FreeBSD: src/lib/libc/sys/profil.2,v 1.9.2.3 2001/12/14 18:34:01 ru Exp $ 33.\" $DragonFly: src/lib/libc/sys/profil.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 34.\" 35.Dd June 4, 1993 36.Dt PROFIL 2 37.Os 38.Sh NAME 39.Nm profil 40.Nd control process profiling 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In unistd.h 45.Ft int 46.Fn profil "char *samples" "size_t size" "vm_offset_t offset" "int scale" 47.Sh DESCRIPTION 48The 49.Fn profil 50function enables or disables 51program counter profiling of the current process. 52If profiling is enabled, 53then at every profiling clock tick, 54the kernel updates an appropriate count in the 55.Fa samples 56buffer. 57The frequency of the profiling clock is recorded 58in the header in the profiling output file. 59.Pp 60The buffer 61.Fa samples 62contains 63.Fa size 64bytes and is divided into 65a series of 16-bit bins. 66Each bin counts the number of times the program counter 67was in a particular address range in the process 68when a profiling clock tick occurred while profiling was enabled. 69For a given program counter address, 70the number of the corresponding bin is given 71by the relation: 72.Bd -literal -offset indent 73[(pc - offset) / 2] * scale / 65536 74.Ed 75.Pp 76The 77.Fa offset 78parameter is the lowest address at which 79the kernel takes program counter samples. 80The 81.Fa scale 82parameter ranges from 1 to 65536 and 83can be used to change the span of the bins. 84A scale of 65536 maps each bin to 2 bytes of address range; 85a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. 86Intermediate values provide approximate intermediate ranges. 87A 88.Fa scale 89value of 0 disables profiling. 90.Sh RETURN VALUES 91.Rv -std profil 92.Sh FILES 93.Bl -tag -width /usr/lib/gcrt0.o -compact 94.It Pa /usr/lib/gcrt0.o 95profiling C run-time startup file 96.It Pa gmon.out 97conventional name for profiling output file 98.El 99.Sh ERRORS 100The following error may be reported: 101.Bl -tag -width Er 102.It Bq Er EFAULT 103The buffer 104.Fa samples 105contains an invalid address. 106.El 107.Sh SEE ALSO 108.Xr gprof 1 109.Sh HISTORY 110A 111.Fn profil 112function call appeared in 113.At v7 . 114.Sh BUGS 115This routine should be named 116.Fn profile . 117.Pp 118The 119.Fa samples 120argument should really be a vector of type 121.Fa "unsigned short" . 122.Pp 123The format of the gmon.out file is undocumented. 124