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