1.\" $OpenBSD: profil.2,v 1.10 2015/09/10 17:55:21 schwarze Exp $ 2.\" $NetBSD: profil.2,v 1.3 1995/11/22 23:07:23 cgd Exp $ 3.\" 4.\" Copyright (c) 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" Donn Seeley of BSDI. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)profil.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd $Mdocdate: September 10 2015 $ 37.Dt PROFIL 2 38.Os 39.Sh NAME 40.Nm profil 41.Nd control process profiling 42.Sh SYNOPSIS 43.In unistd.h 44.Ft int 45.Fn profil "char *samples" "size_t size" "u_long offset" "u_int scale" 46.Sh DESCRIPTION 47The 48.Fn profil 49function enables or disables program counter profiling of the current process. 50If profiling is enabled, then at every clock tick, 51the kernel updates an appropriate count in the 52.Fa samples 53buffer. 54.Pp 55The buffer 56.Fa samples 57contains 58.Fa size 59bytes and is divided into a series of 16-bit bins. 60Each bin counts the number of times the program counter was in a particular 61address range in the process when a clock tick occurred while profiling 62was enabled. 63For a given program counter address, the number of the corresponding bin 64is given by the relation: 65.Bd -literal -offset indent 66[(pc - offset) / 2] * scale / 65536 67.Ed 68.Pp 69The 70.Fa offset 71parameter is the lowest address at which the kernel takes program 72counter samples. 73The 74.Fa scale 75parameter ranges from 1 to 65536 and can be used to change the 76span of the bins. 77A scale of 65536 maps each bin to 2 bytes of address range; 78a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. 79Intermediate values provide approximate intermediate ranges. 80A 81.Fa scale 82value of 0 disables profiling. 83.Sh RETURN VALUES 84If the 85.Fa scale 86value is nonzero and the buffer 87.Fa samples 88contains an illegal address, 89.Fn profil 90returns \-1, profiling is terminated, and 91.Va errno 92is set appropriately. 93Otherwise, 94.Fn profil 95returns 0. 96.Sh FILES 97.Bl -tag -width /usr/lib/gcrt0.o -compact 98.It Pa /usr/lib/gcrt0.o 99profiling C run-time startup file 100.It Pa gmon.out 101conventional name for profiling output file 102.El 103.Sh ERRORS 104The following error may be reported: 105.Bl -tag -width Er 106.It Bq Er EFAULT 107The buffer 108.Fa samples 109contains an invalid address. 110.El 111.Sh SEE ALSO 112.Xr gprof 1 113.\" .Sh HISTORY 114.\" wish I knew... probably v7. 115.Sh BUGS 116This routine should be named 117.Fn profile . 118.Pp 119The 120.Fa samples 121argument should really be a vector of type 122.Fa "unsigned short" . 123.Pp 124The format of the gmon.out file is undocumented. 125