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Re: Maximum memory accessible by Mathematica 6.0 in Windows

• To: mathgroup at smc.vnet.net
• Subject: [mg77564] Re: [mg77544] Maximum memory accessible by Mathematica 6.0 in Windows
• From: Benedetto Bongiorno <bbongiorno at attglobal.net>
• Date: Wed, 13 Jun 2007 07:25:10 -0400 (EDT)
• References: <200706120528.BAA14616@smc.vnet.net>

I have had similar problems for years with prior versions of Mathematica..
It appears the limitation is a combination of Windows XP 32 bit, 
Mathematica 32bit and built in 2GB limitation.
I intend to switch to a laptop with an AMD Turion 64 Dual Core 2.2GHz, 
4GB memory. Vista Ultimate (64bit), Mathematica 6.0 64bit install.
With this, I am told the 4 GB will be available.



L. Dwynn Lafleur wrote:
> Computing Platform:
> Dell PC with Intel Dual Core CPU @ 2.66 GHz
> 4 GB RAM installed
> Windows XP SP2 (Media Center Edition)
>
> -------------------------------------------
>
> As I understand it (see, e.g.,
> http://msdn2.microsoft.com/en-us/library/aa366778.aspx), a single
> application in Windows XP can use to 2 GB of memory (RAM + virtual).
> However, I have not been able get Mathematica 6.0 to use 2 GB, although
> I have been able to do so with other programs, e.g., Python.  With only
> background processes and Windows Task Manager (WTM) running, I load
> Python 2.5.1 through its interactive IDLE shell. After entering the
> command "nn=range(129000000)", the Python shell remains loaded and
> functional, and the Process tab in WTM shows the pythonw.exe process
> using 2,053,644 KB of memory.
>
> OTOH, again with only background processes and WTM running, suppose I
> open Mathematica 6.0 instead of Python.  If I execute the line
>
> nn = Range[312000000]; MaxMemoryUsed[]/(1024.0*1024.0)
>
> the output is "1195.67"; i.e.,  Mathematica reports about 1.2 GB of
> memory being used, and the kernel is still loaded and functional.  At
> that point WTM shows the following memory usages:
>
> MathKernel.exe process ... 1,238,728 KB
> Mathematica.exe process ..    24,712 KB,
> Total Commit Charge ...... 1,528,652 KB (WTM > Performance tab)
>
> (Why a Mathematica list of 312 million integers should require far less
> memory than a Python list of 129 million integers is beside the point
> here; I am only interested in the total memory accessed by the two
> programs.)
>
> If the Range argument in the above Mathematica command were larger by
> a fraction of a percent, I would expect only a small increase in the
> reported memory usage.  Specifically, MathKernel.exe should still use
> well under 2 GB and still be in  functional state. However, when I quit
> the Mathematica kernel, then execute
>
> nn = Range[313000000];MaxMemoryUsed[]/(1024.0*1024.0)
>
> only this message appears:
>
> -------------------------
> No more memory available.
> Mathematica kernel has shut down.
> Try quitting other applications and then retry.
> ------------------------
>
> (WTM verifies that MathKernel.exe is indeed no longer running and that
> Mathematica.exe is using 25,448 KB of memory.)
>
> Am I misunderstanding what is going on?  Shouldn't I be able to get
> Mathematica to use more than about 1.2 GB of memory in Windows XP?  Is
> Mathematica self-limiting the amount of memory it requests from Windows?
>
>   

• References:
  • Maximum memory accessible by Mathematica 6.0 in Windows XP
    • From: "L. Dwynn Lafleur" <lafleur@louisiana.edu>