Operating Systems 2018F Lecture 17: Difference between revisions

From Soma-notes
Created page with "==To Do== * Demo kernel oops in newgetpid * increase storage in remember"
 
No edit summary
Line 1: Line 1:
==To Do==
==Video==


* Demo kernel oops in newgetpid
The video from the lecture on November 9, 2018 [https://homeostasis.scs.carleton.ca/~soma/os-2018f/lectures/comp3000-2018f-lec17-20181109.m4a is now available].
* increase storage in remember
 
==Notes==
 
===In Class===
 
<pre>
Lecture 17
----------
 
Filesystems
 
What is it?
 
 
Well, what's a device file?
- struct file_operations which gives functions for file operations
  (read, write, etc)
 
filesystems just take this idea further
 
 
When you access a file
- process does a file-related system call
- kernel calls generic system call function for requested operation
- kernel calls filesystem-specific function for requested operation
 
e.g.
- process does a write system call on file on an ext4 filesystem
-  kernel runs generic write syscall code
-    kernel runs ext4 write code
 
filesystems are abstractions of file and directory-related operations
- allow many instantiations that we call filesystems
 
filesystems talk to rest of the kernel through a virtual filesystem interface
(VFS)
 
 
Sidebar:
Microkernels vs monolithic kernels
 
Why microkernels
- better security: if a service crashes, it is just a process
- easier development: servers are just a process
 
Why monolithic kernels
- faster
- you depend on it anyway, so security benefits are illusory
</pre>

Revision as of 02:00, 10 November 2018

Video

The video from the lecture on November 9, 2018 is now available.

Notes

In Class

Lecture 17
----------

Filesystems

What is it?


Well, what's a device file?
 - struct file_operations which gives functions for file operations
   (read, write, etc)

filesystems just take this idea further


When you access a file
 - process does a file-related system call
 - kernel calls generic system call function for requested operation
 - kernel calls filesystem-specific function for requested operation

e.g.
 - process does a write system call on file on an ext4 filesystem
 -   kernel runs generic write syscall code
 -     kernel runs ext4 write code

filesystems are abstractions of file and directory-related operations
 - allow many instantiations that we call filesystems

filesystems talk to rest of the kernel through a virtual filesystem interface
 (VFS)


Sidebar:
Microkernels vs monolithic kernels

Why microkernels
 - better security: if a service crashes, it is just a process
 - easier development: servers are just a process

Why monolithic kernels
 - faster
 - you depend on it anyway, so security benefits are illusory