Increase OS X Performance: Swap Partition

[andymoraitis]

PDF Posted

A PDF version of the swapfile hack compressed with Stuffit 6.01 has also been posted and tested for download integrity. The original RTF file has also been maintained.

 

[blakespot]

Reminisce...

Not really relevant to the issue at hand.... But and interesting old tidbit. I recall, when setting up VM on my 486-66 PC that I got to run NEXTSTEP v3.2 for Intel processors ( http://www.blakespot.com/list/images/eCesys1.jpg ), there was a way you could speed up VM accesses. The system I had used an ISA-based SCSI controller, tied to a 700MB Quantum HD (with a big ole' 512K cache--that was an EXPENSIVE drive back then, it sits in my Amiga 2000 presently, 7 yo drive). The VM system in NEXTSTEP allowed you, if you desired, to turn on compression (a simple 2:1 compression) via modifying a config file such as the ones we're dealing with here. As it turns out, it was faster to move 1/2 the amount of data from the drive, through that 8MHz ISA slot, into main memory and have the 486 decompress it before the OS made us of the paged data, than to move the full, uncompressed swap pages to and fro. I remember being surprised at the time--but a 486-66 was a pretty fast chip, back then.

I had to take out a loan, back in the day (3/94) to purchase that system which was strucutred specifically to run NEXTSTEP--it had 16MB of RAM (LOTS of RAM!), 700MB HD, 256K L2 cache, 17" altima screen, all black in color--$4,500.

Ahhh, the memories.




bp

 

[MacUser]

A note to "Mr. Obvious"

Take it somewhere else. Andy is doing this on his own time, just to help out the many, many Mac users who are not familiar with anything related to Unix and the new OS. I, for one, appreciate his efforts.

Likewise, I'm sure the administrators are doing their best. Making things like this OS X tip available can be a tremendous help. Last time I checked, this was not a pay site, so lose the harsh attitude.

 

[Lars 20]

Turning off swap space.

Originally posted by blakespot
Every modern operating system (MacOS 9 is not a moden operating system from a technical perspective) has virtual memory as a standard part of its operation---without the option of turning it off. ...

Unix has always had VM, and all of its flavors (Linux, NeXTSTEP, Solaris, QNX, Irix, etc.).

blakespot

So I assume that you take Linux as a modern OS, with VM and without the option to turn it off.

The statement about not being able to turn off swap is just plain wrong. Of course you _can_ disable VM, at least in Linux and Solaris.

cu
Lars

 

[Dominique]

virtual memory

Your comments on VM and OSX are worrying me. I have a G4 733 with 1152 Mo RAM under OS9.2 and one of the reason why I have not installed OSX (beside I can't see what to use it for as all my DTP and animation application would require classic anyway) is that in the memory control pannel I get a message: virtual memory can't operate with that amount of RAM (or something of that kind). What will happen under OSX will I have to remove RAM to get VM on or what?

 

[andymoraitis]

Dominique,

With 1152 Meg of RAM in OS9, you have no reason to turn virtual memory on in the first place. I'm not sure you're getting memory errors (maybe not enough room on the drive to create an 1153Meg vm file?) in OS9, but as far as OSX is concerned, the kernel can address the maximum that the machine can hold (1.5 Gig).

Also, VM in OSX is always on and cannot be disabled as it's functions are part of the Unix subsystem. So you could load OSX and never have a memory problem. Also, turn off VM in OS9, since it's but a waste of drive space and it's not going to make anything faster.

Hope that helps,

Andy

 

[Dominique]

thanks
In OS9.2 indeed I don't want to use VM (Adobe Premiere and and Finalcut pro...). What I meant was that the choice was not available anyway in memory control pannel. So what will happen when I will use classic (OS9.2) vithout VM over OSX with VM?

 

[andymoraitis]

Classic is not actually another operating system, but an application under OSX. Since you'll be running in OSX, VM functions are on and that's all you really need to worry about. Just because OSX uses VM by default, it doesn't mean that when using Classic that OS9 needs it on as well. Remember, OSX controls Classic and not OS9.

If you do decide to install OSX, I recommend that you create separate partitions for OS9 and OSX. That way you can dual-boot the system by holding down the option key at startup (which will give you a menu of bootable partitions after it scans for devices).

My advice is that if you need heavy duty graphics apps, go ahead and install both systems, keep your main work in OS9 and boot into OSX to see mess around until your apps go native or are Carbonized to work in both. Classic is OK, but if you really want to get the job done, use OS9.

Hope that helps,

Andy