109 lines
3.6 KiB
HTML
109 lines
3.6 KiB
HTML
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<html>
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<head>
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<title>bloat</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>bloat</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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bloat - waste memory
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</p>
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<h3>Synopsis</h3>
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<p>
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<tt>/testbin/bloat</tt>
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[<tt>-a </tt><em>allocs</em>]
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[<tt>-b </tt><em>bias</em>]
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[<tt>-p </tt><em>touchpages</em>]
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</p>
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<h3>Description</h3>
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<p>
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<tt>bloat</tt> allocates all available memory one page at a time until
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it runs out.
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Unlike other tests that do this, it has been gimmicked up so that it
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runs in a fairly reasonable amount of time even when swapping.
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</p>
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<p>
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It runs in cycles; every cycle it allocates <em>allocs</em> pages, one
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at a time, by calling <A HREF=../syscall/sbrk.html>sbrk</A> (not
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<A HREF=../libc/malloc.html>malloc</A>), then touches <em>touchpages</em>
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pages.
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It chooses the pages it touches as follows:
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</p>
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<ul>
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<li><p>
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1 in 1000 pages are chosen uniformly from the entire allocated space.
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</p></li>
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<li><p>
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The rest are taken from the middle 1% of the space; note that this
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range shifts upwards as more pages are allocated.
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</p></li>
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<li><p>
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It rolls <em>bias</em> dice to pick pages from the middle 1%.
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The more dice, the tighter the distribution it picks and the
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faster it runs.
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</p></li>
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</ul>
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<p>
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The default settings are 4 <em>allocs</em>, 8 <em>touchpages</em>
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and a <em>bias</em> of 8.
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This gives reasonable performance with reasonable amounts of memory on
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the solution set.
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There are enough things affecting the speed that you may want to
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experiment with the settings when testing on your own VM system.
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</p>
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<h3>Requirements</h3>
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<p>
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<tt>bloat</tt> uses the following system calls:
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<ul>
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<li><A HREF=../syscall/sbrk.html>sbrk</A></li>
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<li><A HREF=../syscall/write.html>write</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>bloat</tt> should work once you have implemented your VM system
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and added the sbrk system call.
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It may not run fast by default, but it should always be faster than
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<A HREF=sbrktest.html>sbrktest</A> 10 or the notoriously glacial
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<A HREF=malloctest.html>malloctest</A> 3.
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</p>
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</body>
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</html>
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