132 lines
4.1 KiB
Groff
132 lines
4.1 KiB
Groff
.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Donn Seeley of BSDI.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)profil.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd "June 4, 1993"
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.Dt PROFIL 2
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.Os
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.Sh NAME
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.Nm profil
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.Nd control process profiling
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.Sh SYNOPSIS
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.Ft int
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.Fn profil "char *samples" "int size" "int offset" "int scale"
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.Sh DESCRIPTION
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The
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.Fn profil
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function enables or disables
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program counter profiling of the current process.
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If profiling is enabled,
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then at every profiling clock tick,
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the kernel updates an appropriate count in the
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.Fa samples
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buffer.
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The frequency of the profiling clock is recorded
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in the header in the profiling output file.
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.Pp
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The buffer
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.Fa samples
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contains
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.Fa size
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bytes and is divided into
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a series of 16-bit bins.
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Each bin counts the number of times the program counter
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was in a particular address range in the process
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when a profiling clock tick occurred while profiling was enabled.
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For a given program counter address,
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the number of the corresponding bin is given
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by the relation:
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.Bd -literal -offset indent
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[(pc - offset) / 2] * scale / 65536
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.Ed
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.Pp
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The
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.Fa offset
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parameter is the lowest address at which
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the kernel takes program counter samples.
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The
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.Fa scale
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parameter ranges from 1 to 65536 and
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can be used to change the span of the bins.
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A scale of 65536 maps each bin to 2 bytes of address range;
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a scale of 32768 gives 4 bytes, 16384 gives 8 bytes and so on.
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Intermediate values provide approximate intermediate ranges.
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A
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.Fa scale
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value of 0 disables profiling.
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.Sh RETURN VALUES
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If the
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.Fa scale
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value is nonzero and the buffer
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.Fa samples
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contains an illegal address,
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.Fn profil
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returns \-1,
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profiling is terminated and
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.Va errno
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is set appropriately.
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Otherwise
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.Fn profil
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returns 0.
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.Sh FILES
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.Bl -tag -width /usr/lib/gcrt0.o -compact
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.It Pa /usr/lib/gcrt0.o
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profiling C run-time startup file
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.It Pa gmon.out
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conventional name for profiling output file
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.El
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.Sh ERRORS
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The following error may be reported:
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The buffer
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.Fa samples
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contains an invalid address.
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.El
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.Sh SEE ALSO
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.Xr gprof 1
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.\" .Sh HISTORY
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.\" wish I knew... probably v7.
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.Sh BUGS
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This routine should be named
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.Fn profile .
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.Pp
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The
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.Fa samples
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argument should really be a vector of type
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.Fa "unsigned short" .
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.Pp
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The format of the gmon.out file is undocumented.
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