1.\" $NetBSD: profil.2,v 1.14 2016/06/18 14:39:15 kamil Exp $ 2.\" 3.\" Copyright (c) 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Donn Seeley of BSDI. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" @(#)profil.2 8.1 (Berkeley) 6/4/93 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" "unsigned long offset" "unsigned 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 clock tick, 54the kernel updates an appropriate count in the 55.Fa samples 56buffer. 57.Pp 58The buffer 59.Fa samples 60contains 61.Fa size 62bytes and is divided into 63a series of 16-bit bins. 64Each bin counts the number of times the program counter 65was in a particular address range in the process 66when a clock tick occurred while profiling was enabled. 67For a given program counter address, 68the number of the corresponding bin is given 69by the relation: 70.Bd -literal -offset indent 71[(pc - offset) / 2] * scale / 65536 72.Ed 73.Pp 74The 75.Fa offset 76parameter is the lowest address at which 77the kernel takes program counter samples. 78The 79.Fa scale 80parameter ranges from 1 to 65536 and 81can be used to change the span of the bins. 82A scale of 65536 maps each bin to 2 bytes of address range; 83a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. 84Intermediate values provide approximate intermediate ranges. 85A 86.Fa scale 87value of 0 disables profiling. 88.Sh RETURN VALUES 89If the 90.Fa scale 91value is nonzero and the buffer 92.Fa samples 93contains an illegal address, 94.Fn profil 95returns \-1, 96profiling is terminated and 97.Va errno 98is set appropriately. 99Otherwise 100.Fn profil 101returns 0. 102.Sh FILES 103.Bl -tag -width /usr/lib/gcrt0.o -compact 104.It Pa /usr/lib/gcrt0.o 105profiling C run-time startup file 106.It Pa gmon.out 107conventional name for profiling output file. 108This may be different if the PROFDIR environment variable is set. 109.El 110.Sh ERRORS 111The following error may be reported: 112.Bl -tag -width Er 113.It Bq Er EFAULT 114The buffer 115.Fa samples 116contains an invalid address. 117.El 118.Sh SEE ALSO 119.Xr gprof 1 , 120.Xr moncontrol 3 121.\" .Sh HISTORY 122.\" wish I knew... probably v7. 123.Sh BUGS 124This routine should be named 125.Fn profile . 126.Pp 127The 128.Fa samples 129argument should really be a vector of type 130.Fa "unsigned short" . 131.Pp 132The format of the gmon.out file is undocumented. 133