mirror of https://github.com/mkerrisk/man-pages
303 lines
7.7 KiB
Groff
303 lines
7.7 KiB
Groff
.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH SPROF 1 2014-06-24 "Linux" "Linux User Manual"
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.SH NAME
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sprof \- read and display shared object profiling data
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.SH SYNOPSIS
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.nf
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.BR sprof " [\fIoption\fP]... \fIshared-object-path\fP \
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[\fIprofile-data-path\fP]"
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.fi
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.SH DESCRIPTION
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The
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.B sprof
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command displays a profiling summary for the
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shared object specified as its first command-line argument.
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The profiling summary is created using previously generated
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profiling data in the (optional) second command-line argument.
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If the profiling data pathname is omitted, then
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.B sprof
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will attempt to deduce it using the soname of the shared object,
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looking for a file with the name
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.IR <soname>.profile
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in the current directory.
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.SH OPTIONS
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The following command-line options specify the profile output
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to be produced:
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.TP
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.BR \-c ", " \-\-call\-pairs
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Print a list of pairs of call paths for the interfaces exported
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by the shared object,
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along with the number of times each path is used.
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.TP
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.BR \-p ", " \-\-flat\-profile
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Generate a flat profile of all of the functions in the monitored object,
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with counts and ticks.
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.TP
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.BR \-q ", " \-\-graph
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Generate a call graph.
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.PP
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If none of the above options is specified,
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then the default behavior is to display a flat profile and a call graph.
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.PP
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The following additional command-line options are available:
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.TP
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.BR \-? ", " \-\-help
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Display a summary of command-line options and arguments and exit.
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.TP
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.BR \-\-usage
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Display a short usage message and exit.
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.TP
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.BR \-V ", " \-\-version
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Display the program version and exit.
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.SH CONFORMING TO
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The
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.B sprof
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command is a GNU extension, not present in POSIX.1.
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.SH EXAMPLE
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The following example demonstrates the use of
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.BR sprof .
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The example consists of a main program that calls two functions
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in a shared library.
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First, the code of the main program:
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.in +4n
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.nf
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$ \fBcat prog.c\fP
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#include <stdlib.h>
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void x1(void);
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void x2(void);
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int
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main(int argc, char *argv[])
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{
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x1();
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x2();
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exit(EXIT_SUCCESS);
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}
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.fi
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.in
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.PP
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The functions
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.IR x1()
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and
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.IR x2()
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are defined in the following source file that is used to
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construct the shared library:
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.in +4n
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.nf
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$ \fBcat libdemo.c\fP
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#include <unistd.h>
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void
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consumeCpu1(int lim)
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{
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int j;
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for (j = 0; j < lim; j++)
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getppid();
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}
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void
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x1(void) {
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int j;
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for (j = 0; j < 100; j++)
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consumeCpu1(200000);
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}
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void
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consumeCpu2(int lim)
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{
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int j;
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for (j = 0; j < lim; j++)
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getppid();
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}
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void
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x2(void)
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{
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int j;
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for (j = 0; j < 1000; j++)
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consumeCpu2(10000);
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}
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.fi
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.in
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.PP
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Now we construct the shared library with the real name
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.IR libdemo.so.1.0.1 ,
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and the soname
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.IR libdemo.so.1 :
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.in +4n
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.nf
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$ \fBcc \-g \-fPIC \-shared \-Wl,\-soname,libdemo.so.1 \e\fP
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\fB\-o libdemo.so.1.0.1 libdemo.c\fP
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.fi
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.in
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.PP
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Then we construct symbolic links for the library soname and
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the library linker name:
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.in +4n
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.nf
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$ \fBln \-sf libdemo.so.1.0.1 libdemo.so.1\fP
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$ \fBln \-sf libdemo.so.1 libdemo.so\fP
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.fi
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.in
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.PP
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Next, we compile the main program, linking it against the shared library,
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and then list the dynamic dependencies of the program:
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.in +4n
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.nf
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$ \fBcc \-g \-o prog prog.c \-L. \-ldemo\fP
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$ \fBldd prog\fP
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linux\-vdso.so.1 => (0x00007fff86d66000)
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libdemo.so.1 => not found
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libc.so.6 => /lib64/libc.so.6 (0x00007fd4dc138000)
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/lib64/ld\-linux\-x86\-64.so.2 (0x00007fd4dc51f000)
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.fi
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.in
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.PP
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In order to get profiling information for the shared library,
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we define the environment variable
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.BR LD_PROFILE
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with the soname of the library:
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.in +4n
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.nf
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$ \fBexport LD_PROFILE=libdemo.so.1\fP
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.fi
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.in
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.PP
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We then define the environment variable
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.BR LD_PROFILE_OUTPUT
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with the pathname of the directory where profile output should be written,
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and create that directory if it does not exist already:
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.in +4n
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.nf
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$ \fBexport LD_PROFILE_OUTPUT=$(pwd)/prof_data\fP
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$ \fBmkdir \-p $LD_PROFILE_OUTPUT\fP
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.fi
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.in
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.PP
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.B LD_PROFILE
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causes profiling output to be
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.I appended
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to the output file if it already exists,
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so we ensure that there is no preexisting profiling data:
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.in +4n
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.nf
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$ \fBrm \-f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile\fP
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.fi
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.in
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.PP
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We then run the program to produce the profiling output,
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which is written to a file in the directory specified in
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.BR LD_PROFILE_OUTPUT :
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.in +4n
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.nf
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$ \fBLD_LIBRARY_PATH=. ./prog\fP
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$ \fBls prof_data\fP
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libdemo.so.1.profile
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.fi
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.in
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.PP
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We then use the
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.BR "sprof \-p"
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option to generate a flat profile with counts and ticks:
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.in +4n
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.nf
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$ \fBsprof \-p libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
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Flat profile:
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Each sample counts as 0.01 seconds.
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% cumulative self self total
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time seconds seconds calls us/call us/call name
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60.00 0.06 0.06 100 600.00 consumeCpu1
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40.00 0.10 0.04 1000 40.00 consumeCpu2
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0.00 0.10 0.00 1 0.00 x1
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0.00 0.10 0.00 1 0.00 x2
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.fi
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.in
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.PP
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The
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.BR "sprof \-q"
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option generates a call graph:
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.in +4n
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.nf
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$ \fBsprof \-q libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
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index % time self children called name
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0.00 0.00 100/100 x1 [1]
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[0] 100.0 0.00 0.00 100 consumeCpu1 [0]
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\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
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0.00 0.00 1/1 <UNKNOWN>
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[1] 0.0 0.00 0.00 1 x1 [1]
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0.00 0.00 100/100 consumeCpu1 [0]
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\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
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0.00 0.00 1000/1000 x2 [3]
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[2] 0.0 0.00 0.00 1000 consumeCpu2 [2]
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\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
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0.00 0.00 1/1 <UNKNOWN>
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[3] 0.0 0.00 0.00 1 x2 [3]
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0.00 0.00 1000/1000 consumeCpu2 [2]
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\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
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.fi
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.in
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.PP
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Above and below, the "<UNKNOWN>" strings represent identifiers that
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are outside of the profiled object (in this example, these are instances of
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.IR main() ).
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.PP
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The
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.BR "sprof \-c"
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option generates a list of call pairs and the number of their occurrences:
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.in +4n
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.nf
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$ \fBsprof \-c libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
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<UNKNOWN> x1 1
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x1 consumeCpu1 100
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<UNKNOWN> x2 1
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x2 consumeCpu2 1000
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.fi
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.in
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.SH SEE ALSO
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.BR gprof (1),
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.BR ldd (1),
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.BR ld.so (8)
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