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DOS/16M FAQ:
Virtual Memory Manager


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  1. Do you recommend using the DOS/16M Virtual Memory Manager (VMM)?
  2. Are there any other reasons to not use the DOS/16M VMM?
  3. Can a block of memory allocated under the MPreferLow strategy ever be swapped out?

1. Do you recommend using the DOS/16M Virtual Memory Manager (VMM)?

No, mostly because memory is so cheap these days.


2. Are there any other reasons to not use the DOS/16M VMM?

Yes.

The DOS/16M VMM is programmed to run on a 286-class machine, using variable-sized segments of up to 64KB, rather than the fixed-sized 4KB page size of the 386, 486 and Pentium class machines.

It is fairly easy to have performance problems using any VMM system, but particularly when using a segment-oriented VMM like the DOS/16M VMM.


3. Can a block of memory allocated under the MPreferLow strategy ever be swapped out?

Yes, allocations under the MPreferLow strategy might be swapped out, because they could have come from extended memory (which is managed by VMM). MForceLow-allocated memory is not managed by VMM so it won't be swapped out.


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Last modified 2003.02.07. Your questions, comments, and feedback are welcome.