https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Operating_Systems_2021F_Lecture_20 2026-04-06T04:46:32Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2021F_Lecture_20&diff=23564&oldid=prev 2021-11-30T20:26:59Z

<p>Created page with &quot;==Video== Video from the lecture given on November 30, 2021 is now available: * [https://homeostasis.scs.carleton.ca/~soma/os-2021f/lectures/comp3000-2021f-lec20-20211130.m4v...&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on November 30, 2021 is now available:<br /> * [https://homeostasis.scs.carleton.ca/~soma/os-2021f/lectures/comp3000-2021f-lec20-20211130.m4v video]<br /> * [https://homeostasis.scs.carleton.ca/~soma/os-2021f/lectures/comp3000-2021f-lec20-20211130.cc.vtt auto-generated captions]<br /> Video is also available through Brightspace (Resources-&gt;Class zoom meetings-&gt;Cloud Recordings tab)<br /> <br /> ==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 20<br /> ----------<br /> <br /> - for A3Q6, if you reported the results of a reasonable experiment<br /> you can get full credit even if you got the wrong answer<br /> <br /> &quot;Holes&quot; in UNIX files<br /> - why allocate blocks that are storing all 0&#039;s (null bytes)?<br /> - If you write zeros to a file, it will take up space<br /> - however, if you seek past the end of a file and then write,<br /> the space in between will become a &quot;hole&quot; which logically has<br /> null bytes but takes up no space on disk<br /> <br /> in the Linux kernel, processes and kernel threads are represented<br /> as &quot;tasks&quot;<br /> - something that can be scheduled to run on the CPU<br /> <br /> If you want to do something in kernel space that you know how to do from userspace using system calls<br /> - look at how the system call is implemented<br /> &lt;/pre&gt;</div>

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