man-pages/man3/profil.3.html
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<H1>PROFIL</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
profil - execution time profile
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/unistd.h">unistd.h</A>&gt;</B>
<B>int profil(unsigned short *</B><I>buf</I><B>, size_t </B><I>bufsiz</I><B>,</B>
<B> size_t </B><I>offset</I><B>, unsigned int </B><I>scale</I><B>);</B>
</PRE>
Feature Test Macro Requirements for glibc (see
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
<P>
<B>profil</B>():
<PRE>
Since glibc 2.21:
_DEFAULT_SOURCE
In glibc 2.19 and 2.20:
_DEFAULT_SOURCE || (_XOPEN_SOURCE &amp;&amp; _XOPEN_SOURCE&nbsp;&lt;&nbsp;500)
Up to and including glibc 2.19:
_BSD_SOURCE || (_XOPEN_SOURCE &amp;&amp; _XOPEN_SOURCE&nbsp;&lt;&nbsp;500)
</PRE>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
This routine provides a means to find out in what areas your program
spends most of its time.
The argument
<I>buf</I>
points to
<I>bufsiz</I>
bytes of core.
Every virtual 10 milliseconds, the user's program counter (PC)
is examined:
<I>offset</I>
is subtracted and the result is multiplied by
<I>scale</I>
and divided by 65536.
If the resulting value is less than
<I>bufsiz</I>,
then the corresponding entry in
<I>buf</I>
is incremented.
If
<I>buf</I>
is NULL, profiling is disabled.
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUE</H2>
Zero is always returned.
<A NAME="lbAF">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>profil</B>()
</TD><TD>Thread safety</TD><TD>MT-Unsafe<BR></TD></TR>
</TABLE>
<P>
<A NAME="lbAG">&nbsp;</A>
<H2>CONFORMING TO</H2>
Similar to a call in SVr4 (but not POSIX.1).
<A NAME="lbAH">&nbsp;</A>
<H2>BUGS</H2>
<B>profil</B>()
cannot be used on a program that also uses
<B>ITIMER_PROF</B>
interval timers (see
<B><A HREF="/cgi-bin/man/man2html?2+setitimer">setitimer</A></B>(2)).
<P>
True kernel profiling provides more accurate results.
Libc 4.4 contained a kernel patch providing a system call profil.
<A NAME="lbAI">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+gprof">gprof</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?1+sprof">sprof</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?2+setitimer">setitimer</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+signal">signal</A></B>(2)
<A NAME="lbAJ">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="1"><A HREF="#lbAB">NAME</A><DD>
<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="4"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DT id="5"><A HREF="#lbAF">ATTRIBUTES</A><DD>
<DT id="6"><A HREF="#lbAG">CONFORMING TO</A><DD>
<DT id="7"><A HREF="#lbAH">BUGS</A><DD>
<DT id="8"><A HREF="#lbAI">SEE ALSO</A><DD>
<DT id="9"><A HREF="#lbAJ">COLOPHON</A><DD>
</DL>
<HR>
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Time: 00:05:52 GMT, March 31, 2021
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