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Re: Q: OPtimal swap file settings with win3.11

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  • Subject: [mg3950] Re: [mg3867] Q: OPtimal swap file settings with win3.11
  • From: John Fultz <jfultz>
  • Date: Sat, 11 May 1996 23:52:02 -0400
  • Sender: owner-wri-mathgroup at

> Hi, 
> I'm using mma 2.2.1 with windows3.11 and 16 mb ram.
> Often, when doing large calculations, mma quits kernel due to lack of memory,
> despite a large swapfile (48 mb) and giving 24 mb extra to the kernel.
> It seems mma runs into other limitations than memory.
> Indeed 1) the memory meter shows still lots of free memory
> 2) a smaller swap file works just as good
> So what are the optimal settings for swap file size,
> ExtraPages (math.ini) and PagesOverCommit ( system.ini) ??
> Any comments welcom,
> Mark

Your problem is not with the swap file or any Windows settings.
Mathematica 2.2.1 has a hard limit for the size of the kernel
executable and data space for the kernel.  This hard limit can be
adjusted by the user prior to launching the kernel, but may not be
adjusted afterward.  You can do this by choosing the Kernel Settings
under the Options menu.  There is a slider bar that allows you to
allocate between 0 and 12 megabytes for data space.  Unfortunately,
given the paradigm under which 2.2.1 operated, Mathematica runs into a
Windows technological restriction--this restrains the kernel's memory
to a maximum of 16 megabytes (and thus data space for the kernel to 12

The solution is to upgrade your version of Mathematica.  As of
Mathematica 2.2.2, the front-end/kernel paradigm under Windows was
redesigned to allow the kernel to flexibly allocate its own memory.
This solves two problems--one is the hard upper limit which I just
discussed.  The other is the hard lower limit--in case you hadn't
noticed, the kernel in 2.2.1 consumes all of the memory it requires as
soon as it is launched.  The kernel in 2.2.2 and above initially takes
about 4 megabytes for executable space, and then consumes data space
incrementally as it is required.  All in all, it allows for much
smoother operation if your Mathematica operations consume a lot of

The current version of Mathematica for Windows is  You can
obtain it from Wolfram Research for a fee, or if you have a valid
Mathematica Plus subscription, you can exercise it to get the upgrade.
Contact Wolfram Research for more information about this.


John Fultz
jfultz at
Applications Group
Wolfram Research, Inc.


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