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Message-ID: <420F8853.1050108@bellsouth.net>
Date: Sun, 13 Feb 2005 11:03:15 -0600
From: "Charles D. Russell" <worwor AT bellsouth DOT net>
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To: cygwin cygwin <cygwin AT cygwin DOT com>
Subject: What has changed in cygwin's memory access?
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Using a version of cygwin installed around April of '03 I could increase 
the stack size with  gcc flag -Wl,--stack to 256 Mb, but now, on the 
same machine (512 Mb RAM, Windows XP Pro) I can get only 150 Mb using a 
recent cygwin download. What has changed in memory usage since April '03?

In case someone is willing to read the rest of this message even after 
seeing the word "fortran", let me explain my real problem. In April of 
'03 I was able to access 770 Mb of memory for g77 arrays, but using the 
current version of cygwin (on the same computer) I can access only 150 
or 160 Mb using either g77 or gfortran.  I can do better than that (240 
Mb) on my old Windows 98 laptop with only 64 Mb of RAM using a 
4-year-old version of cygwin!  The configuration that worked 
successfully for large fortran arrays in April '03 was:

1) increase allocated memory in cygwin to 1 Gb (from default around 384 
Mb) using:
regtool -i set /HKLM/Software/Cygnus\ Solutions/Cygwin/heap_chunk_in_mb 1024
2) increase stack size to 4 Mb (from default 2Mb) using compiler option:
-Wl,--stack,0x400000
3) increase Windows virtual memory to max paging file size 2048 Mb

What has changed in cygwin  since April '03 to mess up memory access by 
g77 and gfortran?  Can it be reversed by a configuration change?

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