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You are here: MacNN Forums > Enthusiast Zone > Classic Macs and Mac OS > what is the call on vm?

what is the call on vm?
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Mac Elite
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Feb 13, 2001, 07:16 PM
 
i have more then enough ram.... but is it more benificial to have vm on (for say 1 mb) just to get the improved memory handeling.I am in os9.0.4, and will probably upgrade to 9.1 soon.

thanks

There's someone in my head but its not me...
     
Mac Elite
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Feb 13, 2001, 07:44 PM
 
I have 192 MB and I leave Virtual Memory off.

Why?

Because of this quote: "Memory is like an orgasm. It's a lot better if you don't have to fake it." ~ Seymore Cray, on virtual memory.

I agree!

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Fyre4ce

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Feb 13, 2001, 08:15 PM
 
Unless you need it, i.e. you have <128MB RAM, don't use VM. You computer and hard disk will thank you for it.
     
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Feb 13, 2001, 08:34 PM
 
I have a DP 450 G4 with 256mb RAM and I leave VM ON. Even with this amount of RAM with VM off I still have "out of memory" errors and quitting apps still doesn't give it all back.

This is not just my machine, but also several cubes that some friends have that have 512 mb RAM each. The reason? I don't know, but read some of the posts here and you'll see many of the same results.

Your system uses less RAM with VM on, too. Ultimately it's up to you....
     
Mac Elite
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Feb 13, 2001, 10:12 PM
 
As I understand it...

The computer uses memory differently depending on the VM settings. With VM off, when an application is launched, Mac OS loads the entire program into RAM. With VM on, Mac OS only loads in pieces, depeding on what the program needs. This explains why programs take up more RAM and take longer to load with VM off. However, with VM off, once a program loads, it is faster than with VM on. As I stated before, I keep VM off, and my system takes up between 75 and 80 MB. Subtract 16 for a RAM disk, and another 5.5 for disk cache. That leaves about 90 MB for applications. I've never run out, although I have come within 5 or 10 MB of doing so. My recommendation is try using your machine with VM off. If you don't run out of RAM, keep it that way. If you start to run out, either get some more or turn VM on.

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Fyre4ce

"I need a vacation." - Terminator robot
Fyre4ce

Let it burn.
     
Mac Enthusiast
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Feb 13, 2001, 11:12 PM
 
I vote with the "leave it off if you can" side. The most stable way to run apps in OS 9.x is without VM and just give them lots of real RAM (except for open GL games where the idea is to leave yourself tons of unallocated RAM since while running open GL the Mac OS sucks up tons of extra ram). OS X will fix all this since a VERY much improved version of VM is on all the time and all apps (well, Carbon and Cocoa apps - not Classic ones) can just grab as much memory as they ever need and increase and decrease memory allotments dynamically.

[This message has been edited by snodman (edited 02-13-2001).]
     
WDL
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Feb 13, 2001, 11:36 PM
 
This subject just never goes away.

VM is on on all four of my Macs - they seem faster and more stable with it on.

Additionally, Apple, David Pogue and others say it should be on.

Prior to OS 8, VM was a dog. Since OS 8 it has worked very well.

Try a week on and a week off, and you be the judge.

WDL
     
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Feb 13, 2001, 11:40 PM
 
The Mac OS as we know it today (not OS X) was never meant to use VM. So it does slow down the system an increases disk usage/noise. If you can afford more real RAM that is your best bet, but don't be afraid to turn VM on, if you need to then do it...if you can live within the constrains of your amount of physical RAM, then do that.

FYI: When Steve demos the Mac OS (again not OS X) the VM is turned off on the demo machine.
     
Art D
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Feb 14, 2001, 02:31 AM
 
I've got lots of memory and have tried running with and without VM. Frankly, I can't tell any difference (so I leave it off). I don't know if there are any applications that definitely benefit from VM or not. However, I've heard that there are some that actually run slower when VM is turned on. Even Apple recommends not using VM with "Final Cut Pro" for example. They say it causes dropped frames on capture and playback, as well as sluggish performance. Check out this TIL article.

     
Phaedrus
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Feb 14, 2001, 02:45 AM
 
I've found only a few apps that run better with it on, notably Unreal Tournament (higher fps with it on). I have a question, does leaving VM on shorten the life of one's hard drive? It seems that with the system always accessing the hd it would wear out faster. Any thoughts on whether this is significant or not?
     
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Feb 14, 2001, 03:07 AM
 
I suppose the clencher might be Photoshop however I've seen no problems with it yet

OS 9.0.4 ran under 35 MB with Virtual memory OFF on my Beige G3/266 Desktop w/352 MB RAM, since OS 9.1 I've discoverred that it hogs-up ALOT more RAM and actually seems to run fine with VM ON.

I'd always just automatically switched it off in the past, but apparrently it works just fine for me and my place of work.

Mike
     
Clinically Insane
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Feb 14, 2001, 04:18 AM
 
Turn it on to 1 meg.
I have 128 and run VM on 250.
VM makes your computer faster, more stable, and memory management is MUCH improved.
Apps use less RAM with it on too.
Only disadvantage is the loss of disk space. But who cares?
Turn it on.
Any TIL that says its sluggish is dead wrong. Hell at one stage I ran with a gig of VM and there wasn't any slowdown

Turn it off in two situations: FCP, and DVD playing. Thats it.

Cipher13
     
Clinically Insane
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Feb 14, 2001, 04:19 AM
 
Originally posted by error404ts:
I have a DP 450 G4 with 256mb RAM and I leave VM ON. Even with this amount of RAM with VM off I still have "out of memory" errors and quitting apps still doesn't give it all back.

This is not just my machine, but also several cubes that some friends have that have 512 mb RAM each. The reason? I don't know, but read some of the posts here and you'll see many of the same results.

Your system uses less RAM with VM on, too. Ultimately it's up to you....
Have you tried increasing the RAM allocation via the Finders "Get Info" window to alleviate this problem?
Those errors aren't caused by a lack or RAM, but a lack of RAM allocated to the program.

Cipher13
     
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Feb 14, 2001, 05:34 AM
 
Sorry to makes this subject even more divided but I 'know' my setup, and I stress my setup, G4/400 384mb real ram OS 9.1 runs a lot better with VM off. I not saying other like Cipher 13 by no means are wrong I think has to do with setup.
With VM on, a run down of my arrow down a menu say with 6 items I would get 3 'clicks' from the sounds effects, but with VM off I hear every single 'click'. Also windows open and close faster. I have also had less crashes then before.

I agree with 'WDL' that try with it ON then with it OFF. Then make up your mind which is right for you. But i had to do some serious cutting back of 'extensions' to get everything loading right. That was time consuming since it was trial and error.

MM-o4
     
meyer.wasserkuppe
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Feb 14, 2001, 06:15 AM
 
I have 576 MB installed in my G4 (non-AGP). Drive is partioned so that the system has its own partition as well as Photoshop having its own swappable partition. I have dumped sys folders on all partitions (just in case I shoot one doing my wild experiments) and I can quickly boot from any. I never (almost) write anything to my two swap partitions thusly never fragmenting them. Also good is that with the drive partitioned, Norton Util's cleans up the smaller volumes a lot quicker than one big one. I have virtually no down time, and I have no problems doing Photoshop collages of up to 900 MB!

Just wanted to mention this.
     
Clinically Insane
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Feb 14, 2001, 06:54 AM
 
Originally posted by MM-o4:
Sorry to makes this subject even more divided but I 'know' my setup, and I stress my setup, G4/400 384mb real ram OS 9.1 runs a lot better with VM off. I not saying other like Cipher 13 by no means are wrong I think has to do with setup.
With VM on, a run down of my arrow down a menu say with 6 items I would get 3 'clicks' from the sounds effects, but with VM off I hear every single 'click'. Also windows open and close faster. I have also had less crashes then before.

I agree with 'WDL' that try with it ON then with it OFF. Then make up your mind which is right for you. But i had to do some serious cutting back of 'extensions' to get everything loading right. That was time consuming since it was trial and error.

MM-o4
Thats not a fair test. The sound themes are pathetically implemented. They just sit on top of everything else and play a damn sound on certain actions recieved.
having too many damned windows open will make sound themes stuff up.
And isn't it funny you want performance - so you turn off VM. But you have sound themes on...?
But anyway.
I guess it may depend on configuration, but not really...
My system is a G4 400/128/250 VM/10 gig 7200 drive with an System Folder fully customised - if its not in use, its not there.
And its faster with VM than without.
As I've said before - there are 2 things you turn VM off for - DVD's, and FCP.

Cipher13
     
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Feb 14, 2001, 06:57 AM
 
Originally posted by meyer.wasserkuppe:
I have 576 MB installed in my G4 (non-AGP). Drive is partioned so that the system has its own partition as well as Photoshop having its own swappable partition. I have dumped sys folders on all partitions (just in case I shoot one doing my wild experiments) and I can quickly boot from any. I never (almost) write anything to my two swap partitions thusly never fragmenting them. Also good is that with the drive partitioned, Norton Util's cleans up the smaller volumes a lot quicker than one big one. I have virtually no down time, and I have no problems doing Photoshop collages of up to 900 MB!

Just wanted to mention this.
...where does VM come into that?

Cipher13
     
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Feb 14, 2001, 10:24 AM
 
[ I guess it comes in by way of his having VM on and is still very stable? ]

OS X may eventually make it all *moot* but from the varied experiences (and despite all the interesting background on how VM works), the "rules" for whether to use VM or not are awfully hard to generalize (other than if you just don't have enough physical RAM). You may have to test your own config.

I have had the experience of being told by software help desks that their web-access routines will be less likely to have prob with VM on (irregard of how much phys mem). So THEY're sold - though (with Cipher) I often find increasing the app mem alloc is (by trial and error) the more important issue.

Video / Audio: Haven't heard anyone else complain but on my Pismo 400 /9.0.4 I get CD play interruptions when certain HD access is happening *unless* I have VM off.
Have yet to find a workaround.

I gather that Video more consistently has conflicts with VM.

Anyway... once again you're gonna have to experiment around if you expect your memory to be "like an orgasm" as it is reported to be (above).

Don't expect your Valentine to get the same thrill
Pismo 400 192M Sys 9.1
     
Mac Elite
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Feb 14, 2001, 11:54 AM
 
With virtual memory on, my MP3 playback drops out every time there is disk access. Its such a bother, I turned off my VM.

This is on a brand new G4/533dual. I just added RAM up to 384MB and I shouldn't have any further problems. I was astounded that this would be an issue, as my G3/450mHz upgrade on an 8500/180 w/360MB RAM ran flawlessly with or without VM and never stuttered or messed up the MP3 playback.

The only issue I can think that would cause this is the Adaptec 2940U2W PCI SCSI card I have. I'm going to try moving all my data off these drives and reformatting low-level to clear any older drivers and see if that helps. But moving 40GB+ isn't easy.

Anyone else have suggestions?
     
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Feb 14, 2001, 12:04 PM
 
Originally posted by spicyjeff:
The Mac OS as we know it today (not OS X) was never meant to use VM. So it does slow down the system an increases disk usage/noise. If you can afford more real RAM that is your best bet, but don't be afraid to turn VM on, if you need to then do it...if you can live within the constrains of your amount of physical RAM, then do that.

FYI: When Steve demos the Mac OS (again not OS X) the VM is turned off on the demo machine.
There shouldn't be that much hard disk swapping unless your on borrowed memory.

FYI: When Steve demos the Mac OS (again not OS X) the VM is turned off on the demo machine.

-Got any proof to back that up?
     
Phaedrus
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Feb 15, 2001, 01:02 AM
 
Any thoughts on whether or not VM affects the longevitiy of one's hard drive?
     
Clinically Insane
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Feb 15, 2001, 02:21 AM
 
Well, not that much swapping is done - thats why its really moot in a lot of ways. Its just not accessed that often.
But if you're running with 32 megs and 300 virtual on a system that requires 64 megs on its own (like my 5500), the HD will get chewed up bad. But, its still running, so... don't worry about that.
HD's are tough in that respect.

Cipher13
     
Clinically Insane
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Feb 15, 2001, 02:23 AM
 
Originally posted by bluedog:
With virtual memory on, my MP3 playback drops out every time there is disk access. Its such a bother, I turned off my VM.

This is on a brand new G4/533dual. I just added RAM up to 384MB and I shouldn't have any further problems. I was astounded that this would be an issue, as my G3/450mHz upgrade on an 8500/180 w/360MB RAM ran flawlessly with or without VM and never stuttered or messed up the MP3 playback.

The only issue I can think that would cause this is the Adaptec 2940U2W PCI SCSI card I have. I'm going to try moving all my data off these drives and reformatting low-level to clear any older drivers and see if that helps. But moving 40GB+ isn't easy.

Anyone else have suggestions?
What mp3 player are you using?
I use Audion 1.5 on my g4/400/128/250VM and it NEVER skips - no matter what I do to it.
Except ejecting CD's some times. Thats all. Even while restoring the state of VPC it plays flawlessly.
There is a problem with your setup.
Turn up the buffer on your mp3 player.
VM rocks.

Cipher13
     
   
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