232 lines
6.0 KiB
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232 lines
6.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of PTHREAD_ATTR_SETSCOPE</TITLE>
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</HEAD><BODY>
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<H1>PTHREAD_ATTR_SETSCOPE</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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pthread_attr_setscope, pthread_attr_getscope - set/get contention scope
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attribute in thread attributes object
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/pthread.h">pthread.h</A>></B>
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<B>int pthread_attr_setscope(pthread_attr_t *</B><I>attr</I><B>, int </B><I>scope</I><B>);</B>
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<B>int pthread_attr_getscope(const pthread_attr_t *</B><I>attr</I><B>, int *</B><I>scope</I><B>);</B>
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Compile and link with <I>-pthread</I>.
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>pthread_attr_setscope</B>()
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function sets the contention scope attribute of the
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thread attributes object referred to by
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<I>attr</I>
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to the value specified in
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<I>scope</I>.
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The contention scope attribute defines the set of threads
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against which a thread competes for resources such as the CPU.
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POSIX.1 specifies two possible values for
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<I>scope</I>:
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<DL COMPACT>
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<DT id="1"><B>PTHREAD_SCOPE_SYSTEM</B>
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<DD>
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The thread competes for resources with all other threads
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in all processes on the system that are in the same scheduling
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allocation domain (a group of one or more processors).
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<B>PTHREAD_SCOPE_SYSTEM</B>
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threads are scheduled relative to one another
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according to their scheduling policy and priority.
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<DT id="2"><B>PTHREAD_SCOPE_PROCESS</B>
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<DD>
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The thread competes for resources with all other threads
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in the same process that were also created with the
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<B>PTHREAD_SCOPE_PROCESS</B>
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contention scope.
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<B>PTHREAD_SCOPE_PROCESS</B>
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threads are scheduled relative to other threads in the process
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according to their scheduling policy and priority.
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POSIX.1 leaves it unspecified how these threads contend
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with other threads in other process on the system or
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with other threads in the same process that
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were created with the
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<B>PTHREAD_SCOPE_SYSTEM</B>
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contention scope.
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</DL>
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<P>
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POSIX.1 requires that an implementation support at least one of these
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contention scopes.
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Linux supports
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<B>PTHREAD_SCOPE_SYSTEM</B>,
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but not
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<B>PTHREAD_SCOPE_PROCESS</B>.
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<P>
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On systems that support multiple contention scopes, then,
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in order for the parameter setting made by
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<B>pthread_attr_setscope</B>()
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to have effect when calling
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_create">pthread_create</A></B>(3),
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the caller must use
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_setinheritsched">pthread_attr_setinheritsched</A></B>(3)
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to set the inherit-scheduler attribute of the attributes object
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<I>attr</I>
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to
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<B>PTHREAD_EXPLICIT_SCHED</B>.
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<P>
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The
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<B>pthread_attr_getscope</B>()
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function returns the contention scope attribute of the
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thread attributes object referred to by
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<I>attr</I>
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in the buffer pointed to by
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<I>scope</I>.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success, these functions return 0;
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on error, they return a nonzero error number.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<B>pthread_attr_setscope</B>()
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can fail with the following errors:
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<DL COMPACT>
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<DT id="3"><B>EINVAL</B>
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<DD>
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An invalid value was specified in
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<I>scope</I>.
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<DT id="4"><B>ENOTSUP</B>
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<DD>
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<I>scope</I>
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specified the value
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<B>PTHREAD_SCOPE_PROCESS</B>,
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which is not supported on Linux.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>pthread_attr_setscope</B>(),
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<B>pthread_attr_getscope</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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POSIX.1-2001, POSIX.1-2008.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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The
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<B>PTHREAD_SCOPE_SYSTEM</B>
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contention scope typically indicates that a user-space thread is
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bound directly to a single kernel-scheduling entity.
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This is the case on Linux for the obsolete LinuxThreads implementation
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and the modern NPTL implementation,
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which are both 1:1 threading implementations.
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<P>
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POSIX.1 specifies that the default contention scope is
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implementation-defined.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_init">pthread_attr_init</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_setaffinity_np">pthread_attr_setaffinity_np</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_setinheritsched">pthread_attr_setinheritsched</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_setschedparam">pthread_attr_setschedparam</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_attr_setschedpolicy">pthread_attr_setschedpolicy</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pthread_create">pthread_create</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+pthreads">pthreads</A></B>(7)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="11"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="12"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="13"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="14"><A HREF="#lbAK">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:53 GMT, March 31, 2021
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</BODY>
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</HTML>
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