https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Operating_Systems_2014F_Lecture_1 2026-04-22T11:17:08Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19212&oldid=prev 2014-09-10T19:27:12Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:27, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l66">Line 66:</td> <td colspan="2" class="diff-lineno">Line 66:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== Hints for Assignment 1 Question 8: ===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== Hints for Assignment 1 Question 8: ===</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Why is the browser like an operating system?  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Why is the browser like an operating system?  </div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[http://www.theguardian.com/technology/2014/apr/09/software-internet]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* </ins>[http://www.theguardian.com/technology/2014/apr/09/software-internet <ins style="font-weight: bold; text-decoration: none;">Article 1</ins>]</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[https://www.techdirt.com/articles/20080530/0022021266.shtml]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* </ins>[https://www.techdirt.com/articles/20080530/0022021266.shtml <ins style="font-weight: bold; text-decoration: none;">Article 2</ins>]</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[http://www.webopedia.com/DidYouKnow/Hardware_Software/Google_Chrome_OS.asp]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* </ins>[http://www.webopedia.com/DidYouKnow/Hardware_Software/Google_Chrome_OS.asp <ins style="font-weight: bold; text-decoration: none;">Article 3</ins>]</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the scriptable application section.. Think about what happens when you save a word document, and you have added an image, or a script within the file.  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the scriptable application section.. Think about what happens when you save a word document, and you have added an image, or a script within the file.  </div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[http://www.cs.fsu.edu/~awang/courses/cop5611_s2014/not-a-file.pdf]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* </ins>[http://www.cs.fsu.edu/~awang/courses/cop5611_s2014/not-a-file.pdf <ins style="font-weight: bold; text-decoration: none;">Research Paper</ins>]</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19211&oldid=prev 2014-09-10T19:26:09Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:26, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l63">Line 63:</td> <td colspan="2" class="diff-lineno">Line 63:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can&#039;t write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It&#039;s turtles all the way down, see : [[File:Turtles.jpg|200px]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can&#039;t write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It&#039;s turtles all the way down, see : [[File:Turtles.jpg|200px]]</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">=== Hints for Assignment 1 Question 8: ===</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Why is the browser like an operating system? </ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[http://www.theguardian.com/technology/2014/apr/09/software-internet]</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[https://www.techdirt.com/articles/20080530/0022021266.shtml]</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[http://www.webopedia.com/DidYouKnow/Hardware_Software/Google_Chrome_OS.asp]</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">For the scriptable application section.. Think about what happens when you save a word document, and you have added an image, or a script within the file. </ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[http://www.cs.fsu.edu/~awang/courses/cop5611_s2014/not-a-file.pdf]</ins></div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19209&oldid=prev 2014-09-10T19:02:08Z

<p><span dir="auto"><span class="autocomment">Real Hardware</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:02, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l12">Line 12:</td> <td colspan="2" class="diff-lineno">Line 12:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Real Hardware===  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Real Hardware===  </div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>* variable, quirks (bugs, problems, faults, mess-ups / didn't do things right instead they do things differently)  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>* variable, quirks (bugs, problems, faults, mess-ups / didn't do things right<ins style="font-weight: bold; text-decoration: none;">, </ins>instead they do things differently) - abstraction <ins style="font-weight: bold; text-decoration: none;">                                      </ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">* they do things differently </del>- abstraction</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>* most hardware expects a single master <ins style="font-weight: bold; text-decoration: none;">- resource management / sharing</ins></div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>* most hardware expects a single master  </div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>  * most hardware expects to be told what to do by one program, and only one program will actually give it instructions  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>  * most hardware expects to be told what to do by one program, and only one program will actually give it instructions  </div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>  * They need to be consistent, not contradict each other.  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>  * They need to be consistent, not contradict each other.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===On a regular computer we want:===   </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===On a regular computer we want:===   </div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19208&oldid=prev 2014-09-10T18:56:58Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:56, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l63">Line 63:</td> <td colspan="2" class="diff-lineno">Line 63:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It's turtles all the way down, see : [[File:Turtles.jpg]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It's turtles all the way down, see : [[File:Turtles.jpg<ins style="font-weight: bold; text-decoration: none;">|200px</ins>]]</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19207&oldid=prev 2014-09-10T18:56:31Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:56, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l63">Line 63:</td> <td colspan="2" class="diff-lineno">Line 63:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It's turtles all the way down.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It's turtles all the way down<ins style="font-weight: bold; text-decoration: none;">, see : [[File:Turtles</ins>.<ins style="font-weight: bold; text-decoration: none;">jpg]]</ins></div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19205&oldid=prev 2014-09-10T18:48:03Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:48, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l63">Line 63:</td> <td colspan="2" class="diff-lineno">Line 63:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes are very expensive, you can't write too many times to the same sector. It is dead<ins style="font-weight: bold; text-decoration: none;">. You have to spread out your writes using wear leveling. Wait a second, filesystems were made to abstract the writes. You put an operating system on a solid state disk. You are actually running a filesystem on top of a filesystem. We layer this, because if you put your own filesystem on top of it, you will blow it up. Flash drives have operating systems. It's turtles all the way down</ins>.</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19204&oldid=prev 2014-09-10T18:46:30Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:46, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l60">Line 60:</td> <td colspan="2" class="diff-lineno">Line 60:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Here <del style="font-weight: bold; text-decoration: none;">a </del>VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program. If you think about this for a minute. This is crazy. Instead of running one operating system and having each have their own applications. Instead you have one operating system per user. I'm running an extra 50 million lines of code per user. (Example: AMAZON Cloud - Hypervisor - on top of that you are going to run your own instance of the operating system.) Unix was designed as a multi-user operating system. Designed to allow many people to share the same computer. But instead of doing that now we run entire operating systems for one user. This is horribly wasteful. But this is also very useful. It's useful because we can now run different operating systems for different users. Moores' law allows us to be sloppy and lazy. My program only runs well on this particular operating system. (Example: Ubuntu 12.04, well I'll keep a vm around that just runs Ubuntu 12.04)</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Here <ins style="font-weight: bold; text-decoration: none;">the </ins>VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program. If you think about this for a minute. This is crazy. Instead of running one operating system and having each have their own applications. Instead you have one operating system per user. I'm running an extra 50 million lines of code per user. (Example: AMAZON Cloud - Hypervisor - on top of that you are going to run your own instance of the operating system.) Unix was designed as a multi-user operating system. Designed to allow many people to share the same computer. But instead of doing that now we run entire operating systems for one user. This is horribly wasteful. But this is also very useful. It's useful because we can now run different operating systems for different users. Moores' law allows us to be sloppy and lazy. My program only runs well on this particular operating system. (Example: Ubuntu 12.04, well I'll keep a vm around that just runs Ubuntu 12.04) <ins style="font-weight: bold; text-decoration: none;">Today we have resources to burn. How do you take old abstractions and make them work today?</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">Sequential reads are much faster than random reads. </del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks <del style="font-weight: bold; text-decoration: none;">- writes </del>are very expensive, you can't write too many times to the same sector. It is dead.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks <ins style="font-weight: bold; text-decoration: none;">are they a disk? Do they make round chips? No they are chips, they are storage, it is silicon. We understand it that way because the abstraction we use to access it is that disk abstraction. Sequential reads are much faster than random reads. Not true for SSDs. Random reads are the same or faster than sequential reads. Writes </ins>are very expensive, you can't write too many times to the same sector. It is dead.</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19203&oldid=prev 2014-09-10T18:43:03Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:43, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l60">Line 60:</td> <td colspan="2" class="diff-lineno">Line 60:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Here a VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program. If you think about this for a minute. This is crazy. Instead of running one operating system and having each have their own applications. Instead you have one operating system per user. I'm running an extra 50 million lines of code per user. (Example: AMAZON Cloud - Hypervisor - on top of that you are going to run your own instance of the operating system.) Unix was designed as a multi-user operating system. Designed to allow many people to share the same computer. But instead of doing that <del style="font-weight: bold; text-decoration: none;">you </del>run entire operating systems for one user. This is horribly wasteful. <del style="font-weight: bold; text-decoration: none;">Also </del>very useful.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Here a VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program. If you think about this for a minute. This is crazy. Instead of running one operating system and having each have their own applications. Instead you have one operating system per user. I'm running an extra 50 million lines of code per user. (Example: AMAZON Cloud - Hypervisor - on top of that you are going to run your own instance of the operating system.) Unix was designed as a multi-user operating system. Designed to allow many people to share the same computer. But instead of doing that <ins style="font-weight: bold; text-decoration: none;">now we </ins>run entire operating systems for one user. This is horribly wasteful. <ins style="font-weight: bold; text-decoration: none;">But this is also </ins>very useful. <ins style="font-weight: bold; text-decoration: none;">It's useful because we can now run different operating systems for different users. Moores' law allows us to be sloppy and lazy. My program only runs well on this particular operating system. (Example: Ubuntu 12.04, well I'll keep a vm around that just runs Ubuntu 12.04)</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Sequential reads are much faster than random reads.  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Sequential reads are much faster than random reads.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks - writes are very expensive, you can&#039;t write too many times to the same sector. It is dead.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks - writes are very expensive, you can&#039;t write too many times to the same sector. It is dead.</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19202&oldid=prev 2014-09-10T18:41:35Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:41, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l60">Line 60:</td> <td colspan="2" class="diff-lineno">Line 60:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Virtual Machines===</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Here a VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program.  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Here a VM I'm talking about is using Virtualbox. This is used to talk about virtualizing resources. (for example: Virtualbox). You are going to be running an operating system as a program. <ins style="font-weight: bold; text-decoration: none;">If you think about this for a minute. This is crazy. Instead of running one operating system and having each have their own applications. Instead you have one operating system per user. I'm running an extra </ins>50 million lines of code per user. <ins style="font-weight: bold; text-decoration: none;">(Example: AMAZON Cloud - </ins>Hypervisor - on top of that you are going to run your own instance of the operating system.<ins style="font-weight: bold; text-decoration: none;">) </ins>Unix was designed as a multi<ins style="font-weight: bold; text-decoration: none;">-</ins>user operating system. Designed to allow many people to share the same computer. But instead of doing that you run entire operating systems for one user. This is horribly wasteful. Also very useful.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>50 million lines of code per user. Hypervisor - on top of that you are going to run your own instance of the operating system. Unix was designed as a multi user operating system. Designed to allow many people to share the same computer. But instead of doing that you run entire operating systems for one user. This is horribly wasteful. Also very useful.</div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Sequential reads are much faster than random reads.  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Sequential reads are much faster than random reads.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks - writes are very expensive, you can&#039;t write too many times to the same sector. It is dead.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Solid state disks - writes are very expensive, you can&#039;t write too many times to the same sector. It is dead.</div></td></tr> </table>

Afry https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F_Lecture_1&diff=19201&oldid=prev 2014-09-10T18:40:09Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:40, 10 September 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l54">Line 54:</td> <td colspan="2" class="diff-lineno">Line 54:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Things are slowing down a bit. Intel is staying on this curve. Other companies are falling behind, because it is becoming really expensive to stay on it. It is an exponential curve. They never go on forever, they cannot. [http://en.wikipedia.org/wiki/Moore%27s_law Wikipedia of Moore&#039;s Law] This is why you can fit a billion transistor&#039;s in your pocket. CPU, RAM and other devices are driven by transistors. One underlying theme to keep in the back of your mind, realize the abstractions that we are using today, were all developed in the late 60&#039;s and early 70&#039;s. The systems that those things were created for had MB of RAM. Now you are carrying around devices with GBs of RAM in your pocket. Abstractions of operating systems at a fundamental level are trying to deal with how to do these things, but the things underneath become bigger, the abstractions aren&#039;t so useful. If you have code that used the old abstractions you can&#039;t just throw them away.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Things are slowing down a bit. Intel is staying on this curve. Other companies are falling behind, because it is becoming really expensive to stay on it. It is an exponential curve. They never go on forever, they cannot. [http://en.wikipedia.org/wiki/Moore%27s_law Wikipedia of Moore&#039;s Law] This is why you can fit a billion transistor&#039;s in your pocket. CPU, RAM and other devices are driven by transistors. One underlying theme to keep in the back of your mind, realize the abstractions that we are using today, were all developed in the late 60&#039;s and early 70&#039;s. The systems that those things were created for had MB of RAM. Now you are carrying around devices with GBs of RAM in your pocket. Abstractions of operating systems at a fundamental level are trying to deal with how to do these things, but the things underneath become bigger, the abstractions aren&#039;t so useful. If you have code that used the old abstractions you can&#039;t just throw them away.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"> </del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Virtual Machines <del style="font-weight: bold; text-decoration: none;">- </del>talk about virtualizing resources <del style="font-weight: bold; text-decoration: none;">- </del>(for example: Virtualbox). <del style="font-weight: bold; text-decoration: none;">you </del>are going to be running an operating system as a program.  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">How many files are on your computer? Talking like 100,000 files is no big deal. That's a lot of files. A filesystem is a way of abstracting hard disks, a hierarchical storage for naming things. How useful is that abstraction for finding things with hundreds of millions of files. Not that useful, it's too big. Can you get rid of it, no because you still use it to do things. Weird thing about IOS - there is no shared filesystem on IOS. They divided up the applications to remove shared filesystem. A usability issue - users would lose the files. What is a camera roll? it's files, they give you your contacts - that's a database stored in multiple files on your filesystem. The point I'm trying to make, because of Moore's law a lot of the abstraction that you are going to learn in the course are kind of quaint. They are not going away. They are the plumbing. </ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">The classic theme of this is something called:</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">===</ins>Virtual Machines<ins style="font-weight: bold; text-decoration: none;">===</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Here a VM I'm talking about is using Virtualbox. This is used to </ins>talk about virtualizing resources<ins style="font-weight: bold; text-decoration: none;">. </ins>(for example: Virtualbox). <ins style="font-weight: bold; text-decoration: none;">You </ins>are going to be running an operating system as a program.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>50 million lines of code per user. Hypervisor - on top of that you are going to run your own instance of the operating system. Unix was designed as a multi user operating system. Designed to allow many people to share the same computer. But instead of doing that you run entire operating systems for one user. This is horribly wasteful. Also very useful.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>50 million lines of code per user. Hypervisor - on top of that you are going to run your own instance of the operating system. Unix was designed as a multi user operating system. Designed to allow many people to share the same computer. But instead of doing that you run entire operating systems for one user. This is horribly wasteful. Also very useful.</div></td></tr> </table>

Afry