<!-- Copyright (c) 2015 The President and Fellows of Harvard College. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. --> <html> <head> <title>bloat</title> <link rel="stylesheet" type="text/css" media="all" href="../man.css"> </head> <body bgcolor=#ffffff> <h2 align=center>bloat</h2> <h4 align=center>OS/161 Reference Manual</h4> <h3>Name</h3> <p> bloat - waste memory </p> <h3>Synopsis</h3> <p> <tt>/testbin/bloat</tt> [<tt>-a </tt><em>allocs</em>] [<tt>-b </tt><em>bias</em>] [<tt>-p </tt><em>touchpages</em>] </p> <h3>Description</h3> <p> <tt>bloat</tt> allocates all available memory one page at a time until it runs out. Unlike other tests that do this, it has been gimmicked up so that it runs in a fairly reasonable amount of time even when swapping. </p> <p> It runs in cycles; every cycle it allocates <em>allocs</em> pages, one at a time, by calling <A HREF=../syscall/sbrk.html>sbrk</A> (not <A HREF=../libc/malloc.html>malloc</A>), then touches <em>touchpages</em> pages. It chooses the pages it touches as follows: </p> <ul> <li><p> 1 in 1000 pages are chosen uniformly from the entire allocated space. </p></li> <li><p> The rest are taken from the middle 1% of the space; note that this range shifts upwards as more pages are allocated. </p></li> <li><p> It rolls <em>bias</em> dice to pick pages from the middle 1%. The more dice, the tighter the distribution it picks and the faster it runs. </p></li> </ul> <p> The default settings are 4 <em>allocs</em>, 8 <em>touchpages</em> and a <em>bias</em> of 8. This gives reasonable performance with reasonable amounts of memory on the solution set. There are enough things affecting the speed that you may want to experiment with the settings when testing on your own VM system. </p> <h3>Requirements</h3> <p> <tt>bloat</tt> uses the following system calls: <ul> <li><A HREF=../syscall/sbrk.html>sbrk</A></li> <li><A HREF=../syscall/write.html>write</A></li> <li><A HREF=../syscall/_exit.html>_exit</A></li> </ul> </p> <p> <tt>bloat</tt> should work once you have implemented your VM system and added the sbrk system call. It may not run fast by default, but it should always be faster than <A HREF=sbrktest.html>sbrktest</A> 10 or the notoriously glacial <A HREF=malloctest.html>malloctest</A> 3. </p> </body> </html>