Hi Prentice, list
Intel Fortran (at least the 10. and 11.something versions I have)
has different "memory models" for compilation. The default is "small".
The PGI compiler has a similar feature, IIRR.
Have you tried -mcmodel=medium or large?
I never used large, but medium helped a few times on x86_64/i64em.
Of course your available RAM may be restriction,
as David pointed out.
An excerpt from "man ifort" is enclosed below.
I hope this helps,
Gus Correa
---------------------------------------------------------------------
Gustavo Correa
Lamont-Doherty Earth Observatory - Columbia University
Palisades, NY, 10964-8000 - USA
---------------------------------------------------------------------
From "man ifort":
-mcmodel= <mem_model> (i64em only; L*X only)
Tells the compiler to use a specific memory model to
generate
code and store data. This option can affect code size
and per-
formance.
You can specify one of the following values for <mem_model>:
· small
Restricts code and data to the first 2GB of address
space. All
accesses of code and data can be done with Instruction
Pointer
(IP)-relative addressing. This is the default.
· medium
Restricts code to the first 2GB; it places no memory
restric-
tion on data. Accesses of code can be done with
IP-relative
addressing, but accesses of data must be done with
absolute
addressing.
· large
Places no memory restriction on code or data. All
accesses of
code and data must be done with absolute addressing.
If your program has COMMON blocks and local data with a
total
size smaller than 2GB, -mcmodel=small is sufficient.
COMMONs
larger than 2GB require -mcmodel=medium or
-mcmodel=large.
Allocation of memory larger than 2GB can be done with
any set-
ting of -mcmodel.
IP-relative addressing requires only 32 bits, whereas
absolute
addressing requires 64-bits. IP-relative addressing is
somewhat
faster. So, the small memory model has the least impact
on per-
formance.
Note: When the medium or large memory models are
specified, you
must also specify option -shared-intel to ensure that
the cor-
rect dynamic versions of the Intel run-time libraries
are used.
When shared objects (.so files) are built,
position-independent
code (PIC) is specified so that a single .so file can
support
all three memory models. The compiler driver adds option
-fpic
to implement PIC.
However, you must specify a memory model for code that
is to be
placed in a static library or code that will be linked
stati-
cally.
David Mathog wrote:
Prentice Bisbal <prent...@ias.edu> wrote:
Question: What is the maximum number of elements you can have in a
double-precision array in Fortran? I have someone creating a
4-dimensional double-precision array. When they increase the dimenions
of the array to ~200 million elements, they get this error:
compilation aborted (code 1).
The two things that come immediately to mind are:
1. The compiler ran out of memory. (In addition to the size of the
memory in the machine, check ulimit.)
2. The compiler is trying to build the program with 32 bit pointers and
it cannot address this array, or perhaps all memory accessed, with a
pointer of that size. If that is the issue using 64 bit pointers should
solve the problem, but I can't tell you what compiler switches are
needed to do this.
Regards,
David Mathog
mat...@caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech
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