117 lines
4.0 KiB
HTML
117 lines
4.0 KiB
HTML
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<html>
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<head>
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<title>multiexec</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>multiexec</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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multiexec - run many exec calls at once
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</p>
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<h3>Synopsis</h3>
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<p>
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<tt>/testbin/multiexec</tt> [-j <em>nprocs</em>]
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[<em>prog</em> [<em>arg</em> ...]]
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</p>
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<h3>Description</h3>
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<p>
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<tt>multiexec</tt> forks several subprocesses and then uses user-level
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semaphores to cause them to all enter
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<A HREF=../syscalls/execv>execv</A> at as close as possible to the
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same time.
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This is useful for seeing what happens if having too many argv buffers
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in use at once causes the kernel to run into problems, or to test the
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efficacy of measures to mitigate those problems.
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</p>
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<p>
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The default number of subprocesses is 12.
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The default program each subprocess runs is <A HREF=../bin/pwd.html>pwd</A>.
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Other larger programs can be run by giving the program name and
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arguments on <tt>multiexec</tt>'s command line.
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</p>
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<h3>Requirements</h3>
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<p>
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<tt>multiexec</tt> uses the following system calls:
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<ul>
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<li><A HREF=../syscall/getpid.html>getpid</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/close.html>close</A></li>
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<li><A HREF=../syscall/remove.html>remove</A></li>
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<li><A HREF=../syscall/fork.html>fork</A></li>
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<li><A HREF=../syscall/execv.html>execv</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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</ul>
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</p>
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<p>
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<tt>multiexec</tt> should work once you have implemented the basic
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system calls.
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Exactly what the requirements are for handling large multiexec
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invocations is up to your course staff, although probably at a minimum
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your kernel shouldn't crash.
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</p>
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<p>
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Until you implement remove, which is typically not part of the basic
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system calls assignment, <tt>multiexec</tt> will not be able to clean
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up after itself.
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This is untidy but not a problem.
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</p>
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<h3>Bugs</h3>
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<p>
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<tt>multiexec</tt> has a compiled-in limit of 64 words in the argv
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array to be passed to its subprocesses.
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Also, there should be an easy way to pass a very large argv.
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In the meantime, perhaps try having <tt>multiexec</tt> run
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<A HREF=bigexec.html>bigexec</A>.
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</p>
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<h3>Restrictions</h3>
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<p>
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Be aware that until you do the VM assignment and replace dumbvm,
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running a lot of execs will run the system out of memory very
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rapidly.
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</p>
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</body>
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</html>
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