Subject: Re: Linux emulation, binary software, cluster/grid and SMP
To: Bruce O'Neel <>
From: George Georgalis <>
List: tech-cluster
Date: 01/19/2006 05:35:42
On Thu, Jan 19, 2006 at 09:45:13AM +0000, Bruce O'Neel wrote:
>On Wed, Jan 18, 2006 at 11:20:31AM -0500, George Georgalis wrote:
>> The intel site makes it look like you need Intel cpu, but thoes
>> quotes are from Intel Fortran requirements, and I think it will
>> work on AMD, plus Linux emul for NetBSD.
>We've run older versions on amd systems and they have worked fine.  The
>resulting code (no processor specific switches set though) has also worked
>You might want to think hard about g95.  The Intel compiler is likely
>to produce faster code, of course, but g95 has gotten really good 
>recently.  We also find that:
>- it requres less patches than the intel compiler to deal with
>odd corners of F90/F95.
>- it's way less of a pain to install.
>- you don't have a bizzaro website to navigate to get updates.
>- the executables are much smaller.
>oneel@isdclin6:~ > ls -hl /isdc/integration/osa_int/current_linux/bin/ii_skyimage
>-rwxr-xr-x    1 oneel    obs_gen      7.9M Jan 11 16:02 /isdc/integration/osa_int/current_linux/bin/ii_skyimage
>oneel@isdclin6:~ > ls -hl $ISDC_ENV/bin/ii_skyimage
>-rwxr-xr-x    1 isdc_cms obs_gen       23M Nov 29 14:38 /isdc_sw/osa_sw/osa_sw-5.1/gcc/3.2.2/bin/ii_skyimage
>oneel@isdclin6:~ > 
>The bigger one is built with ifc.  Plus the ifc one requires fortran specific 
>shared libraries.  Oh, and the ifc one is stripped and the g95 one isn't.
>We've not seen huge differences between the generated code.  That said,
>we don't set cpu specific optimization flags, nor has it been carefully 
>measured.  Ie, we could have g95 be say 20% slower and we probably wouldn't
>notice it.    We can't easily use CPU specific optimizations since our cluster
>ends up not completely homogeneous.  Ie, we have some xenons, some amd systems,
>and now we're getting some amd dual core systems.  

Thanks Bruce, that's just the kind of perspective I'm looking for.
We are concerned that clients or vendors will _require_ the intel
compiler, so we should be prepared for that.

// George

George Georgalis, systems architect, administrator <IXOYE>< cell:646-331-2027