150 lines
4.8 KiB
HTML
150 lines
4.8 KiB
HTML
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<html>
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<head>
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<title>schedpong</title>
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<link rel="stylesheet" type="text/css" media="all" href="../man.css">
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</head>
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<body bgcolor=#ffffff>
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<h2 align=center>schedpong</h2>
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<h4 align=center>OS/161 Reference Manual</h4>
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<h3>Name</h3>
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<p>
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schedpong - scheduler pong
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</p>
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<h3>Synopsis</h3>
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<p>
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<tt>/testbin/schedpong</tt> [<em>options...</em>]
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</p>
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<h3>Description</h3>
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<p>
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<tt>schedpong</tt> forks a number of processes that do different kinds
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of work.
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This can be used to evaluate the behavior of your scheduler under
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different conditions.
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</p>
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<p>
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There are three kinds of jobs in schedpong:
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<ul>
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<li>Thinkers</li>
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<li>Grinders</li>
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<li>Pong groups</li>
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</ul>
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</p>
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<p>
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A thinker job is one CPU-bound process: it loops computing and doesn't
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sleep for I/O or use much memory.
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</p>
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<p>
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A grinder job is one memory-bound process: it loops accessing lots of
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memory, similar to the various VM stress tests.
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</p>
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<p>
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A pong group job is a family of I/O-bound processes.
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An arbitrary number of processes play scheduler pong using the user
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semaphores (semfs), each process signalling the next.
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</p>
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<p>
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By choosing different numbers of thinkers, pong groups, and grinders,
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and adjusting the pong group size, one can evaluate how well a
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scheduler does under different conditions.
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In general schedulers should be favoring the pong groups in order to
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minimize the response latency of the semaphore ponging, but without
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starving the thinkers.
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Adding grinders to the mix lets your deal with what happens when you
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also have swapping going on, which is a complicated situation not
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handled well by textbook algorithms.
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</p>
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<p>
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Note that you need to have a real VM system (not dumbvm) to use
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grinders.
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With dumbvm you may also need to configure a fair amount of memory to
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get all the intended processes to fork successfully.
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</p>
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<p>
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Options:
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<dl>
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<dt>-t N</dt><dd>Configure N thinkers. (default 2)</dd>
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<dt>-g N</dt><dd>Configure N grinders. (default 0)</dd>
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<dt>-p N</dt><dd>Configure N pong groups. (default 1)</dd>
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<dt>-s N</dt><dd>Set the pong group size to N. (default 6)</dd>
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</dl>
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</p>
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<h3>Requirements</h3>
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<p>
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<tt>schedpong</tt> uses the following system calls:
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<ul>
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<li><A HREF=../syscall/__time.html>__time</A></li>
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<li><A HREF=../syscall/open.html>open</A></li>
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<li><A HREF=../syscall/read.html>read</A></li>
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<li><A HREF=../syscall/write.html>write</A></li>
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<li><A HREF=../syscall/lseek.html>lseek</A></li>
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<li><A HREF=../syscall/close.html>close</A></li>
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<li><A HREF=../syscall/fork.html>fork</A></li>
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<li><A HREF=../syscall/waitpid.html>waitpid</A></li>
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<li><A HREF=../syscall/_exit.html>_exit</A></li>
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<li><A HREF=../syscall/remove.html>remove</A></li>
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<li><A HREF=../syscall/sbrk.html>sbrk</A></li>
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</ul>
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Only the grinder jobs use sbrk, and remove is only used for cleaning
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up.
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</p>
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<p>
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However, note that schedpong relies heavily on the user semaphores;
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if they do not work (owing e.g. to bugs in open/read/write) schedpong
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will not work either.
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Make sure <A HREF=usemtest.html>usemtest</A> runs (at least up to the
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"shoot" test, even if that part doesn't) before spending time on
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schedpong.
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</p>
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<p>
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<tt>schedpong</tt> without grinders should work once you have
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implemented the basic system calls and they work reliably
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(particularly fork).
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<tt>schedpong</tt> with grinders should work once you have implemented
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the sbrk system call and a virtual memory system that supports dynamic
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memory allocation.
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</p>
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</body>
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</html>
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