> < ^ Date: Sun, 16 Nov 2003 20:25:14 -0700 (MST)
> < ^ From: Alexander Hulpke <hulpke@math.colostate.edu >
< ^ Subject: Re: Maximum allocable memory

Dear GAP-Forum,

Roberto Radina asked:

What is the maximum amount of memory that can be allocated? There is any
difference between Unix and Windows?
In a Window2000 machine with 1.5 GB of main memory apparently I can only get
127MB (with -m 128M GAP says that can't extend the workspace).

As Steve Linton already wrote, GAPs memory manager reaches inherent limits
at 2GB (in the next release 4GB).
Under Unix the memory you can allocate (up to this limit) is only bound by
your main and virtual memory.

Under Windows, the `cygwin' environment which we use imposes limits of its
own: Programs are restricted to 128MB (or in newer versions 384MB) or
workspace. To increase this limit (following the manual at
http://www.cygwin.com/cygwin-ug-net/setup-maxmem.html ) it is necessary to
edit the registry:

WARNING: You can seriously damage your Windows installation by changing
registry values in the wrong way. If the following description sounds too
technical please get help from your system administrator before attempting
this change by yourself.

Run the registry editor `regedit' (in the `windows' directory; if you have
the full version of `cygwin' installed you can use the `regtool' program)
and go to HKLM/Software/Cygnus Solutions/Cygwin

If no entry `heap_chunk_in_mb' is set, create such an entry.

Set the value of the `heap_chunk_in_mb' entry to the desired maximum (make
sure you set it in decimal mode, not in hex mode) value in MB.

After the change, newly started GAP jobs will be able to utilize more

Best wishes,

Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, Fort Collins, CO 80523, USA
email: hulpke@math.colostate.edu, Phone: ++1-970-4914288

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