System 7 offers you the ability to 'extend' the available memory by pretending your Macintosh has more RAM than it actually has installed. Instead, the Mac uses a file on disk to store portions of the RAM it currently doesn't need in order to make room for another portion it needs to use now. This way of extending memory is called virtual memory (VM), and it happens transparently for the applications, except for one thing: speed. The so-called swapping of portions of RAM from and to the disk causes your computer to slow down considerably. The larger you set the virtual memory size, the slower your Mac will get. You have to seek a trade-off between the benefits of extra available memory and the speed degradation. VM tuner will help you to determine what's the optimal setting for you and your computer.
2. How does it work ?
VM Tuner will observe the way you use your computer over a relatively long period of time. The statistics it collects will help you determine the optimal setting for VM for your computer and the way you use it.
VM Tuner calculates how large the VM memory setting must be, in order to extend your memory at virtually no speed cost. This is possible because the Macintosh Multifinder does a very bad job at memory management, so bad that in fact 25% up to 50% of the installed RAM in your Mac is "wasted" (because of fixed memory partitions for the applications). The VM Tuner settings are calculated in such a way that this RAM will be used without causing any swapping (or speed degradation). This process is explained more clearly below.
3. Who needs to use VM Tuner ?
In order to be able to use VM Tuner, you need to be able to run VM. This is only possible for Macintoshes which have an MMU (memory management unit). If you don't have an MMU, VM Tuner will tell you so. Every 68030 based Mac has an MMU, some 68020 based Macs also have an MMU. The 68000 based Macs never have an MMU.
I'd like to make a difference between to groups of VM users. The first small group uses only one or two programs which need a lot of memory. An example of such an application is Photoshop. The user only switches between applications occasionally. VM Tuner is of little use to this group of users.
The second and largest group uses more applications and switches more often between them. You are very likely to belong to this group. VM Tuner is aimed at this second group. Even if you don't use VM now, you should run VM Tuner. Perhaps you will discover you can use the RAM in your Macintosh more efficiently without a speed degradation.
Remember that the only thing VM Tuner does is give you some advice on how to set the VM memory size of your computer. It remains up to you to follow this advice or not. VM Tuner is quite conservative when it suggests a setting. You should be the ultimate judge on what you need. Perhaps you don't care about the speed degradation VM causes, and perhaps you are only interested in obtaining a large (virtual) memory space.
Also remember that using VM may cause some compatibility problems with the software you already use. Unless you want to spend a lot of money on upgrading, it really isn't worth using VM in that case.
4. How to use VM Tuner
It is very simple to operate VM Tuner. Just Launch the application (you could also drop VM Tuner in your 'Startup Items' folder), switch it to background and continue working on you Macintosh as you always do. It doesn't matter if you already use VM or not. Every five minutes, VM Tuner will collect some information on the memory usage on your machine.
Note: if you use VM Tuner for the first time, you will be presented a dialog box which will request you to fill out you name and serial number. This dialog box will continue to appear each time you launch the app, until you register your copy . See for details at the end of this document.
After a couple of hours of usage, switch back to VM Tuner and select the Results… menu item. You will be presented with a dialog like this one:
The report will tell you the Physical RAM size (= real installed RAM), the Logical RAM size (=VM memory size) and the average partition usage (explained below) . It will then give you a recommendation on how large you should set your VM memory size. Finally it will give you some comments on your current settings. You can change the current settings by using the memory control panel. Switch VM on, select the appropriate memory setting and reboot.
If VM Tuner suggests two settings (like 6Mb or 7Mb in the example), you should decide what you want. If you want to play it safe, use the lowest figure. The highest figure may cause a very slight speed degradation because of some swapping.
Tip: if you decide to start using virtual memory, you really ought to de-fragment your hard disk with a utility like Norton Utilities Speed Disk or DiskExpress II. The expense of these utilities will certainly pay off in a noticeable speed gain, not only in swapping, but in general hard disk speed.
Note: Some Macs like the Mac II, IIx, IIcx and SE/30 are do not have 32-bit clean ROMs. This is no problem, as long as you don't need to increase the VM settings beyond 13Mb (and/or have no more than 8Mb of RAM installed). However, if you need to do this, you should install an init/cdev called Mode-32, which is freely available for all Macintosh users (consult your dealer about this).
After you have followed the recommendations and changed your settings, you should run VM Tuner again, because the new settings might change the way you use your computer and thus the results. In fact, you should continue to use VM Tuner on a regular basis (every month or so), because the way you work might change.
The longer you run VM Tuner, the more accurate the report will be. You should at least run VM Tuner a couple of hours before getting a report, but preferably a couple of working days. VM Tuner remembers the collected data if you quit it (even if you shut down or restart your Mac). If you re-launch VM Tuner, it will continue to add observations to it's database. You can erase the past observations by selecting the Initialize menu item. You should do this every time you change the settings of VM, or if you install new RAM, run new inits, install new applications and versions or change application memory partitions.
Note: VM Tuner is shareware. If you run an unregistered copy, VM Tuner will not remember the collected data if you quit it. If you forget to get a report before you shut down your computer, all data will be lost. You can read below how to register your copy.
5. The Basic principles of VM Tuner
Note: For clarity, some things are simplified so that non-technical people can understand this text.
When you run multiple applications on your Mac, these applications share the available memory. Each application gets a pre-determined fixed memory partition when it is launched. This is the "current size" setting of the application you see when you click on the application and select Get Info in the finder. You can change this size to accommodate your needs.
When you would make a snapshot of memory at a certain moment in time you would get a picture like this:
In this example, the available memory is split up between the system and two applications. There is also some free memory.
Actually the situation is a bit more complicated than that. The partition size for an application is large enough to accommodate the maximum memory the application will ever need. On average, the application will only use a part of the memory that is allocated for it. You can see this in the following picture:
You can see that both applications leave a large part of the allocated memory unused (the white areas in the middle of the reserved partitions). And here comes the bad part: the unused memory can not be used by any other application. This means your Mac typically only uses 50% to 80% of the installed memory. What a waste !! You can actually see this on your computer when you select About this Macintosh in the finder:
In this example, the Belgian PostCards application only uses about half the memory (532Kb) allocated to it. This is typical for most applications.
Here's where VM comes in. You remember that VM uses a part of the disk to extend your available memory. Instead of 5 Mb you suddenly get, say 7 Mb of RAM. When you use the extra memory, some other part of the RAM will be swapped to disk to make room for the extra memory. And here comes the trick: VM can and will use the unused and 'wasted' RAM for this purpose. And as long as the unused memory remains unused, it will never be swapped back into RAM again.
Hey, but what would happen if you set the VM memory size to the size of the physical RAM plus the average size of unused memory ? Well, eh, …, the computer would perform (almost) no swapping. Wow ! This means if I can find the average size of wasted memory, I could run VM without any speed degradation. There's no magic to this, we're just using the installed RAM more efficiently. The effect is the same as if all unused memory was thrown back onto a heap, where it could be used by all other applications.
Here's what VM Tuner does. It registers the average partition usage (see the report) and with a mathematical formula, it extrapolates the optimal settings for VM.
The average partition usage will be different for each Macintosh user, because it depends on how you use your computer. VM Tuner also needs to be able to observe your memory usage for longer periods of time, so you should run a registered copy as long and as often as possible.
Try it, and make more efficient use of installed RAM.
6. Shareware
This software is shareware. This is not another term for free software, as many people seem to think. Shareware software must be paid, just like ordinary commercial software. The difference is that a shareware author uses cheap distribution channels to keep costs down and this system also allows you to evaluate the software before you decide to purchase it.
Support the shareware system by paying your shareware fee ! Many great shareware products have gone commercial because people did not take up their responsibility and paid their fees.
Remember: unregistered copies of VM Tuner will not save collected statistics before quit. This means that you can not run an unregistered copy for a prolonged period of time, which is necessary to get good results. The unregistered copies are fully functional in all other aspects.
Distribution:
You can distribute this software by giving it away to friend, upload it to a BBS or online services like Compuserve or AOL, or send it to any ftp site. Basically you can distribute it any way you like, as long as you don't ask any money for it, other than a small charge related to distribution costs (cost of a disk, postage or download fee) and keep it together with this unmodified document in the original compressed archive this product came in.
You may not sell this product or bundle it with any other products (commercial or other) without explicit written permission by the author of this software.
You may not modify VM Tuner or this document in any way nor distribute VM Tuner without this document or the other files and applications that came with it.
Price:
The basic fee for the first copy of VM Tuner is $15. For each additional Macintosh you run this product on, you must pay another $5. Mind you: you don't pay for the number of users, but for the number of Macs you run VM Tuner on.
You will receive a personal registration number which will reflect the number of copies you paid for . Please allow 4 to 5 weeks for response.
You can also get a site license for $200. This gives you the right to use as many copies as you want . You will also receive all new updates for free and I will give full support to the best of my possibilities.
Payment:
a. Europe: You can send cash (dollars or Belgian Franks (BEF)) or send me a Eurocheck. The Eurocheck must be made payable in Belgian Franks (BEF). The fee is 450 BEF for the first copy and 150 BEF for each additional Mac. A site license costs 6000 BEF.
b.Outside Europe: You can send cash (dollars) or an International Money Order . Please do not send any checks because cashing a foreign check is often more expensive than the amount it was written for.
From contacts with people in the U.S.A, I learned many people don't pay shareware fees because they think it is a hassle to get money to Europe. It isn't ! The simplest way (for small fees, less than $40), is to send CASH. My experience tells me this is a very reliable method, and I never had any trouble with it. Put the money inside a piece of paper (the registration form) and put it in a firm envelope, so that you can't see it when you hold it to the light. Send the letter by air mail. Larger amounts can best be paid by International Money Order.
My address:
Karl Pottie
Orkaanstraat 21
8800 Rumbeke-Roeselare
Belgium (Europe)
If you want to send me a bug report, be sure to state Macintosh model, system version, used inits (system extensions) and cdevs (control panels). Describe the problem as clearly as you can: what happens ? which circumstances ? Can you eliminate the problem by turning off some extensions ?
LIMITED WARRANTY AND LIABILITY:
THIS SOFTWARE COMES 'AS IS'. I CAN NOT BE HELD RESPONSIBLE FOR ANY DAMAGE OR LOSS OF DATA CAUSED BY THIS PRODUCT DIRECTLY OR INDIRECTLY, WHATEVER THE NATURE OF THE DAMAGE. I CAN NOT BE HELD RESPONSIBLE FOR ANY OF THE ASSUMPTIONS OR IDEAS EXPRESSED IN THIS DOCUMENT, NOR DO I GUARANTEE THE CORRECTNESS OF THESE IDEAS OR ASSUMPTIONS ON WHICH THIS SOFTWARE IS BASED.
