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<!ENTITY title "FreeBSD KSE Project">
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<head>
<title>&title;</title>
<cvs:keyword xmlns:cvs="http://www.FreeBSD.org/XML/CVS">$FreeBSD$</cvs:keyword>
</head>
<body class="navinclude.about">
<h2>Contents</h2>
<ul>
<li><a href="#overview">Project Overview</a></li>
<li><a href="#using">Using KSE</a></li>
<li><a href="#further.reading">Further Reading</a></li>
<li><a href="#status.kernel">Project Status</a></li>
</ul>
<a id="overview" name="overview"></a>
<h2>Overview</h2>
<p>Kernel Scheduler Entities (KSE), is a kernel-supported threading
system similar in design to Scheduler Activations [Anderson, et. al.]. It
strikes a balance between user-level (1:N) and kernel-level (1:1)
threading models, giving most of the advantages of both, and
few of the disadvantages of either.</p>
<p>There are two halves of this project: kernel support and user
support. The kernel support consists of modifications to the
FreeBSD scheduler; The user half is a &posix; threads implementation
which takes advantage of the extra facilities the kernel provides.</p>
<p>The goal is to replace the current user threading system provided by
the libc_r library, and the <tt>-pthread</tt> gcc option, with a new
libpthread library which will be linked with the <tt>-lpthread</tt>
gcc option.</p>
<a name="using"></a>
<h2>Using KSE</h2>
<p>All KSE development is being done in 5.0-CURRENT. No special
kernel configuration options are required to build a kernel with
the KSE-related changes (the changes are inextricable from the
FreeBSD scheduler).</p>
<p>In order to use KSE in an application, you need to link it against
libpthread; this is straightforward. In the application's makefile(s),
change the <tt>-pthread</tt> compiler switch or <tt>-lc_r</tt> link
option to <tt>-lpthread</tt> and relink. Alternatively, you can use
<tt>/etc/libmap.conf</tt> to map libc_r to libpthread (see
<tt>libmap.conf(5)</tt>).</p>
<a name="further.reading"></a>
<h2>Further Reading</h2>
<ul>
<li><a href="http://www.aims.net.au/chris/kse/">
Kernel-Scheduled Entities for FreeBSD</a>, by Jason Evans.
(Slightly out of date).
</li>
<li><a href="http://www.FreeBSD.org/cgi/man.cgi?query=kse&apropos=0&sektion=0&manpath=FreeBSD+5.0-current&format=html">KSE man page</a>
</li>
<li><a href="http://people.FreeBSD.org/~deischen/docs/Scheduler.pdf">
Scheduler Activations</a>, by Anderson, et al.
</li>
</ul>
<a name="status.kernel"></a>
<a name="status"></a>
<h2>Project Status</h2>
<p>Following is an incomplete general list of tasks:</p>
<table class="tblbasic">
<tr>
<th> Module </th>
<th> Task </th>
<th> Responsible </th>
<th> Last updated </th>
<th> Status </th>
</tr>
<tr>
<td> libpthread </td>
<td> Write kse(2) man page documenting new system calls. </td>
<td> &a.archie; </td>
<td> 10 September 2002 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Repo-copy the libpthread library from libc_r. </td>
<td> cvs meister </td>
<td> 16 September 2002 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Use KSE to schedule processes. </td>
<td> &a.mini; </td>
<td> 30 October 2002 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Schedule an idle context when appropriate. </td>
<td> &a.mini; </td>
<td> 2 November 2002 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Deliver signals to threads. </td>
<td> &a.deischen; &a.davidxu; </td>
<td> 28 June 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Locking for SMP. </td>
<td> &a.deischen; </td>
<td> 3 May 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> kernel </td>
<td> Locking for SMP. </td>
<td> &a.davidxu; </td>
<td> 3 May 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Launch multiple KSEs (one per CPU). </td>
<td> &a.davidxu; </td>
<td> 3 May 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread, kernel </td>
<td> Implement alpha machine-dependent functions. </td>
<td> &a.marcel; </td>
<td> 30 Aug 2003 </td>
<td> &status.wip; </td>
</tr>
<tr>
<td> libpthread, kernel </td>
<td> Implement amd64 machine-dependent functions. </td>
<td> &a.davidxu; &a.deischen; </td>
<td> 30 Aug 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread, kernel </td>
<td> Implement i386 machine-dependent functions. </td>
<td> &a.davidxu; &a.deischen; </td>
<td> 30 Aug 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread, kernel </td>
<td> Implement ia64 machine-dependent functions. </td>
<td> &a.marcel; </td>
<td> 30 Aug 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread, kernel </td>
<td> Implement sparc64 machine-dependent functions. </td>
<td> &a.jake; </td>
<td> 30 Aug 2003 </td>
<td> &status.wip; </td>
</tr>
<tr>
<td> kernel </td>
<td> Implement KSE-specific signaling. </td>
<td> &a.davidxu; </td>
<td> 28 June 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> libpthread </td>
<td> Implement scope system threads. </td>
<td> &a.deischen; </td>
<td> 3 May 2003 </td>
<td> &status.done; </td>
</tr>
<tr>
<td> kernel </td>
<td> Efficient scope system threads (no upcalls when they block). </td>
<td> &a.davidxu; </td>
<td> 30 Aug 2003 </td>
<td> &status.done; </td>
</tr>
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<td> </td>
<td> </td>
<td> D M 2002 </td>
<td> &status.new; </td>
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</table>
</body>
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