Defragmenting memory in OS 9

Question

Level 1

38 points

Defragmenting memory in OS 9

I've searched the forums but it's impossible to find anything on this. Too many people use "memory" to refer to hard disk space, most OS 9 issues are dealing with "classic" mode, there are OSX postings in this category, etc.

So....does anyone know how to defregment / free up memory, i.e. RAM, in OS 9 without restarting? I could swear i had a utility to do this, but can't find it now. I've got over 400 Megs of RAM free, but it's all in chunks smaller than 100MB so i can't open Lightwave.

I'm talking about a Mac booted in OS 9, not classic mode. Thanks.

8500/G4, Mac OS 9.2.x

Posted on Oct 26, 2009 5:40 PM

Reply

Answer 1

Niel

Level 10

741,851 points

Oct 26, 2009 5:43 PM in response to paulpen

Quit all applications and relaunch them. If desired, use an AppleScript or utility to quit background processes as well.

(48258)

Reply

Answer 2

paulpen Author

Level 1

38 points

Oct 26, 2009 5:46 PM in response to Niel

I tried that. Well, i quit everything except RAMdisk (AppDisk) which launches on startup. I can't quit that because lots of stuff is there. The largest block size did not increase. If i run "More about this Mac" it shows a bunch of apparently contiguous free blocks, but they are apparently not contiguous to the OS.

Reply

Answer 3

Oct 26, 2009 5:48 PM in response to paulpen

Is Virtual Memory ON? There may be more the OS can do if Virtual Memory is in use.

Reply

Answer 4

paulpen Author

Level 1

38 points

Oct 26, 2009 6:10 PM in response to Grant Bennet-Alder

No, never. Virtual memory is off because i have 768MB of RAM. That should be plenty for OS9.

Reply

Answer 5

Niel

Level 10

741,851 points

Oct 26, 2009 6:42 PM in response to paulpen

Virtual memory should be on whenever possible on a PowerPC Mac running Mac OS 9 or earlier regardless of how much RAM is installed in the machine; click here for more information.

(48259)

Reply

Answer 6

paulpen Author

Level 1

38 points

Oct 26, 2009 7:05 PM in response to Niel

Hmm, that's interesting. I never read that particular article before. However, it states:

In a sampling of native Power Macintosh applications, we found the average RAM required to launch an application was almost 2 MB less when virtual memory was enabled.

That's insignificant today. Moreover, i believe that running apps with VM disabled results in less disk usage and faster performance once the app is loaded into the application partition in RAM. Am i wrong? In any case, speed isn't really the concern. I don't care if Photoshop takes 2.5 seconds to render a filter instead of 2 secs. Plus, Photoshop 5.5 is only about 15 MB which is also insignificant when i have 768MB.

So, interesting factors to consider, but i'm still looking for that utility to free up/defragment RAM without having to restart....

Reply

Answer 7

Oct 27, 2009 5:47 AM in response to paulpen

Mac OS 9 (and 8 and 7) use RAM in the following way:
memory address 0 through about 10,000: core OS
memory address 767,000,000 through 768,000,000: file system (in YOUR system). The file system is always loaded at the high end of RAM - whatever size that RAM may be.

All other addresses are available for the OS to use in a transitory way such as applications, system extensions and background processes.

The basic architecture of the OS is such that once a block of memory is allocated to a specific task (application) it must remain in that location until the application is ended (Quit).

Thus, there exists no tool that will fundementally alter that basic architecture. BUT you may be able to find a copy of a little tool that graphically DISPLAYS how RAM is being used on your system. The tool is called PEEK-A-BOO. It is currently available for X only but you may be able to locate an older version that works with OS 9. Such a version DOES exist.

Gary

Reply