Virtual Memory allows you to pretend you have more memory (RAM) than actually exists on your machine. In the old days, all of an application would be loaded into memory so you couldn't have more apps in memory than your RAM could take, so for instance using that model a Windows machine with 64MB of RAM could probably only have MSIE and Word open before using up all of system memory. With virtual memory, you pretend you have a whole bunch of memory by only loading parts of each app at a time yet the app thinks that it's all in memory at once. That way I can have Word, IE, Excel, Powerpoint and Emacs open at the same time without using up all of my system memory. The way this is done is via a process called paging where parts of the program are retrieved from disk when needed and older uneeded parts are unloaded and written back to disk if modified.

The post I linked to is claiming that we should go back to a model where all of an app is loaded into memory. This would eliminate the constant reading and writing to disk involved in paging but now people would have to run fewer apps with the same amount of memory and program startup would balloon since all of a program would have to be loaded into memory first before running, plus unloading an app would also involve much longer writes to disk.

Anyway, speaking of operating system stuff, the Linux kernel sucks. Not for any reasons of performance or quality mind you but because of the problems highlighted in this post. No one thinks of commenting anything and instead just throws in their hacky code with comments like
/* You aren't supposed to understand this */
The projects in my operating systems class have all been fairly trivial to implement BUT have taken days to do because we've wasted so much time trying to figure out what anything does simply because no one bothers to comment anything. Whenever comments do occur they are completely arbitrary (one commented function in a file with 10 or 15) and contain miniscule amounts of information. *sigh*

By the way, Yes I know that this isn't much better in commercial products (and in fact is typically quite worse) but that doesn't make it right.

By the way, Steve Gibson is a fraud.


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