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RE: Cygwin Memory Allocation and heap_chunk_in_mb

> -----Original Message-----
> From: cygwin-owner On Behalf Of Dan Hatton
> Sent: 30 June 2004 14:55

> I'm using CYGWIN_NT-5.1, under XP Pro.
> I've set my heap_chunk_in_mb registry key to a very large value (10240
> decimal,) because I'm doing some RAM-hungry numerical calculations.
> I have enough space to do this (Control Panel->System reports 12 GB of
> virtual memory allocated.)
> However, the max_memory program at
> <> still reports
> only 1.5 GB available.  Sure enough, my program dies with an "out of
> memory" error at 1.25 GB (the 0.25 GB discrepancy is about right for
> the amount of RAM other processes are using.)
> Anyone got any ideas what's happening, please?

Errm... just checking the obvious, but.... you _are_ using a 64-bit system,

Because no amount of virtual memory can get around the fact that there's
only 4Gb of addresses in the per-process memory space, and 2Gb of those
belong to the kernel.

Of course, even if you are on a 64bit system, cygwin itself isn't 64-bit.
malloc (as used by that test program) returns a 32-bit pointer.  There's no
way of allocating more than 4Gb without malloc having to start returning
duplicate values!

Try adding a line to your boot.ini to allow you to boot with the /3Gb
switch, and see if that gets you an extra gig of memory.  See;EN-US;833721 
for details.

Can't think of a witty .sigline today....

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