On Mon, Feb 28, 2000 7:10 PM, Davis' Mac Works
<mailto:[EMAIL PROTECTED]> wrote:
> Substituting virtual memory for real memory is ok for short-term needs,
but
> if your work routinely needs more memory than you have installed, you
need
> to install more memory.
> 

I think the key to getting the most out of virtual memory is to remember
it's limitations. When using vm, you need to make sure that you have enough
physical ram to run your most memory-hungry application and your system
heap at its worst. The problem today with calculating that figuret is that
many programs use shared libraries. Microsoft programs use these, as does
OpenDoc (Cyberdog--my fav). These shared libraries, instead of being loaded
into the program's memory partition (visible in  the "About this Computer"
window) are loaded into the system heap, possibly ballooning it to two or
even three times its normal space. (BTW, turning on file mapping by turning
on VM allows the system heap to control these shared libraries in a more
memory-efficient manner)

Either way, once you have that all-important figure, you can know whether
or not you need to add physical ram. I would suggest having enough physical
ram to handle your two most-used/biggest programs and your system heap.
This is the safest, and will reduce crashes tremendously. I have always
noticed my crashes start occuring when I'm moving in and out of programs
with a bloated system heap, or I suddenly increase my ram load. 

To help with memory-related crashes, it would be a good policy to restart
your computer once or twice a day. This purges your memory, and gives you
an opportunity for a quick water break. You can be assured that if you
don't do it in a controlled manner, you will be forced to via a crash. :-)

The above is a big portion of what I have learned through experience--trial
and error, and mostly error. :-)

I suppose, in advance of my detractors, I should toss in a caveat here. If
you can afford the ram, especially on powerbooks, you should certainly get
it. It does reduce problems, and is much faster and more energy efficient.
:-)

-Jon Glass
Krakow, Poland
<mailto:[EMAIL PROTECTED]>
<mailto:[EMAIL PROTECTED]>





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