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From:	Mark Hadfield <m DOT hadfield AT niwa DOT co DOT nz>
Subject:	Re: Memory for large arrays in cygwin/g77
Date:	Tue, 11 Jan 2005 10:17:53 +1300
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Dave Korn wrote:
>>From: cygwin-owner On Behalf Of Mark Hadfield
> 
>>Dante R. Chialvo wrote:
>>
>>>2) Use g77 using the Wl option, ie,
>>>
>>> g77 -O2 -o mybigprogram -Wl,--stack,100000000  mybigprogram.f 
>>
>>That's odd. Increasing the stack size definitely does not 
>>work for me. 
>>It just causes the program to terminate silently, with no output.
> 
>   It's more random than that.  The size of the stack isn't the critical issue
> here, since the array isn't on the stack, it's in the .bss section.  The issue
> is the knock-on effects that specifying different initial stack sizes have at
> the time the executable image is mapped into memory, and the subsequent
> allocation or availability of the memory area for the cygheap.

Woooaaa (not "whoa" meaning "stop" but "woooaaa" as in the word used ca 
1995 in movies like "Wayne's World" to indicate a combination of 
surprise and puzzlement).

So, Dave, we've established that Cygwin g77 is not reliable for large 
data arrays. In an earlier message in this thread you cited a couple of 
messages that gave some gory details:

   http://www.cygwin.com/ml/cygwin/2004-10/msg01188.html
   http://www.cygwin.com/ml/cygwin/2004-07/msg00646.html

I must say they're a bit too gory for me to understand.

Is there a cure that would allow a simple-minded, grey-haired Fortran 
programmer like me to rely on Cygwin g77 (or gfortran) for 
moderate-sized computational tasks?

-- 
Mark Hadfield            "Ka puwaha te tai nei, Hoea tatou"
m DOT hadfield AT niwa DOT co DOT nz
National Institute for Water and Atmospheric Research (NIWA)


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