topic Re: RAM limit on em64t in Intel® Fortran Compiler

RAM limit on em64t

moukouri — Fri, 06 Jan 2006 05:04:39 GMT

I thought that the em64t technology works like a true 64 bit system.
But I am experiencing memory limitation to 2.6 GB on a total of 4GB on a dual xeon em64t. I have tried some of the options suggested in
this forum like using allocatable arrays or the compiler option -mcmodel (I could not find it on the non-commercial version of ifort
V8 or V9) or -i-dynamic but I could not exceed 2.6 GB. My OS is
Red-Hat enterprise 3. Can I get any help?

Thanks

Re: RAM limit on em64t

Lorri_M_Intel — Fri, 06 Jan 2006 06:17:49 GMT

What version of the compiler are you using (found using ifort -what anyfile.f)? We've found/fixed a number of bugs where we weren't keeping the full size correctly internally in the compiler. Maybe you have an older vintage?

Also, if possible, an example of what is failing would be interesting.

Thanks -

- Lorri

Re: RAM limit on em64t

moukouri — Fri, 06 Jan 2006 23:26:44 GMT

I am using both v8 and v9 versions of the compiler. This is a simple code I am testing:

PROGRAM mult
IMPLICIT NONE
INTEGER, PARAMETER :: n=10700
INTEGER :: i,j,k
REAL(8), DIMENSION (:,:), ALLOCATABLE :: a,b,c

ALLOCATE(a(n,n),b(n,n),c(n,n))
a=1.;b=2.;c=0.
DO i=1,n
DO j=1,n
Do k=1,n
c(i,j)=a(i,k)*b(k,j)
END DO
END DO
END DO
DEALLOCATE(a,b,c)
END PROGRAM

I am compiling using: ifort -i-dynamic mult.f90

Re: RAM limit on em64t

Steven_L_Intel1 — Fri, 06 Jan 2006 23:33:23 GMT

Which specific versions? 9.0.??? 8.1.??? (You can't be using 8.0 on EM64T.)

You need -mcmodel medium or -mcmodel large as well.

Re: RAM limit on em64t

moukouri — Sat, 07 Jan 2006 00:13:13 GMT

My compiler versions are

l_fc_p_8.1.018 and l_fc_c_9.0.031

Re: RAM limit on em64t

moukouri — Sat, 07 Jan 2006 00:29:27 GMT

Neither of the two compilers seem to recognize the option -mcmodel. Is-it included in the non-commercial version?

Re: RAM limit on em64t

Steven_L_Intel1 — Sat, 07 Jan 2006 00:36:15 GMT

Yes. The non-commercial version is identical. Are you using the EM64T compiler? You may be using the IA32 compiler instead. You have to do the source from the .../fce/... directory.

Please show a log of the command you type and the output when you try to compile the program.

Re: RAM limit on em64t

moukouri — Sat, 07 Jan 2006 02:05:41 GMT

ifort -i-dynamic -mcmodel large mult.f90
ifort: Command line warning: ignoring unknown option '-mcmodel'
ld: cannot open large: No such file or directory

I may well be using the ia32 version. But doesn't the install
script automatically identify the system ia32, em64t or ia64?
Do I need to specify anything more to call the em64t version?

Re: RAM limit on em64t

Steven_L_Intel1 — Sat, 07 Jan 2006 03:01:41 GMT

You need to specify the proper ifortvars.sh script. For EM64T, that would be /opt/intel/fce/9.0/bin/ifortvars.sh