1.\" $NetBSD: profil.2,v 1.9 2002/02/08 01:28:20 ross 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. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" @(#)profil.2 8.1 (Berkeley) 6/4/93 38.\" 39.Dd June 4, 1993 40.Dt PROFIL 2 41.Os 42.Sh NAME 43.Nm profil 44.Nd control process profiling 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.Fd #include \*[Lt]unistd.h\*[Gt] 49.Ft int 50.Fn profil "char *samples" "size_t size" "u_long offset" "u_int scale" 51.Sh DESCRIPTION 52The 53.Fn profil 54function enables or disables 55program counter profiling of the current process. 56If profiling is enabled, 57then at every clock tick, 58the kernel updates an appropriate count in the 59.Fa samples 60buffer. 61.Pp 62The buffer 63.Fa samples 64contains 65.Fa size 66bytes and is divided into 67a series of 16-bit bins. 68Each bin counts the number of times the program counter 69was in a particular address range in the process 70when a clock tick occurred while profiling was enabled. 71For a given program counter address, 72the number of the corresponding bin is given 73by the relation: 74.Bd -literal -offset indent 75[(pc - offset) / 2] * scale / 65536 76.Ed 77.Pp 78The 79.Fa offset 80parameter is the lowest address at which 81the kernel takes program counter samples. 82The 83.Fa scale 84parameter ranges from 1 to 65536 and 85can be used to change the span of the bins. 86A scale of 65536 maps each bin to 2 bytes of address range; 87a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on. 88Intermediate values provide approximate intermediate ranges. 89A 90.Fa scale 91value of 0 disables profiling. 92.Sh RETURN VALUES 93If the 94.Fa scale 95value is nonzero and the buffer 96.Fa samples 97contains an illegal address, 98.Fn profil 99returns \-1, 100profiling is terminated and 101.Va errno 102is set appropriately. 103Otherwise 104.Fn profil 105returns 0. 106.Sh FILES 107.Bl -tag -width /usr/lib/gcrt0.o -compact 108.It Pa /usr/lib/gcrt0.o 109profiling C run-time startup file 110.It Pa gmon.out 111conventional name for profiling output file. This may be different if the PROFDIR environment variable is set. 112.El 113.Sh ERRORS 114The following error may be reported: 115.Bl -tag -width Er 116.It Bq Er EFAULT 117The buffer 118.Fa samples 119contains an invalid address. 120.El 121.Sh SEE ALSO 122.Xr gprof 1 , 123.Xr moncontrol 3 124.\" .Sh HISTORY 125.\" wish I knew... probably v7. 126.Sh BUGS 127This routine should be named 128.Fn profile . 129.Pp 130The 131.Fa samples 132argument should really be a vector of type 133.Fa "unsigned short" . 134.Pp 135The format of the gmon.out file is undocumented. 136