[lkml]   [1998]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: New Feature Idea: Compress swap file
On Fri, 20 Feb 1998, Peter T. Waltenberg wrote:

> There's also the problem of mapping between swapped pages on disk and in
> memory. At the moment it's 4k in mem<->4k on disk, working out where the
> pages are going to and coming from is trivial and there's no real chance
> of fragmenting the swap space.
> If we compress, the pages on disk are variable sized, once you've paged
> in and out a few hundred times we could easilly fragment the swap space to
> hell :).
> Then what ?, stall while we defragment the swap space.

Of course not! We'll use lossy coding!!!!!

First we perform a transform..

Hmm.. Lets say we use.. hmm.. A fourier transform!

Okay.. So we take a 4k page.. Transform it (hey, 4k = 2**12 we can use a
radix FFT!) drop the second half of the output (it's a mirror images of
the first).. Hmm.. Now what? Okay I got it!.. We compute the magnitude of
the complex values of the first half so we can toss the imagnary part..
Who needs phase anyways <snicker>!!!!

But thats only 2:1 compression.. We need more!

Okay now we quantize!

See poof! it all fits into a single 1k block! Tada!

> Keep it simple.
> Peter

Well... I admit all the floating point in the kernel might be a problem..
But hey, this is Linux.. We can accomplish anything.. Even compressing
arbratary random numbers!! (I'm sure we can, there is about a post a week
on the compression newsgroup.. All we need is a RNG that describes the
data.. :))

Hey!!!!! I just heard MS was going to do this in NT5.0 --

"NT5.0 Active-Memory Service (tm) is a new breakthrough in memory
technoligy. By emulating natural memory systems (such as your own), NT5.0
builds a tighter relationship with the user. Microsoft research has shown
that many people expirence empathy with their computer when it fails to
rember simple things, such as the location of it's page tables.

Furthermore, with Active-Memory Service (tm), it's now possible to operate
a MS exchange server with tens of users with less then 512MB (note:
Microsoft defines a megabyte as 2^32 bytes).

We at Microsoft feel that Active-Memory Service will destroy
compea^H^H^H^H^H^H barriers preventing users from expirencing computers
the way Gates intended them to..." -- MS Press

Hey.. It doesn't sound so bad... After all.. It couldn't reduce NT's
stability at all.. Could it?

(Note to the Humor impared: This was a Joke! If you didn't laugh, then
please dont reply :) )..

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to

 \ /
  Last update: 2005-03-22 13:41    [W:0.125 / U:0.732 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site