[Pw_forum] AMD64 and IFC

[Ralph Gebauer]

We have been doing some performance-tests of opterons with
many programs.

In general, the performance (using 64-bit compiled versions)
is quite good with respect to dual pentium 4s (one dual
opteron equals approx. two dual P4s). This is mainly a result
of the very good scalability from 1 to 2 processors on the
opteron.

These results apply to tests of cpmd, fpmd, and some classical
md programs, NOT to pwscf.

With pwscf and the pgi 5.0 compiler we are able to obtain
a binary executable, however, that executable only works
for very small systems. In bigger systems, the program
crashes with segmentation faults, which result clearly from
a compiler bug. This error is reproducable on a 32 bit
compilation with the same pgi 5.0 compiler on a pentium 4,
so it is not opteron related.

We will soon check pgi 5.1 and the absoft compilers. But up to now,
we could not run pwscf properly on an opteron in 64 bit mode.

Ralph


-- 
Ralph Gebauer
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Condensed Matter Section           Tel: (+39).040.2240.344
Strada Costiera 11                 Fax: (+39).040.224163
I-34014 Trieste (Italy)            e-mail: rgebauer at ictp.trieste.it



Paolo Giannozzi wrote:
> On Thursday 29 January 2004 17:13, Jonathan Breeze wrote:
> 
> 
>>I am soon to be the lucky recipient of an AMD64 computer [....]
>>When I come to compiling PWSCF, I'll need to know :
>>1) Can one compile 64-bit code for AMD using the Intel Fortran
>> Compiler? If not, is there a compiler that can ?
> 
> 
> I have heard that you can compile 32-bit executables with Intel
> compilers, but it is not very fast, and that the only compiler that
> compiles 64-bit code on AMD is PGI. The CVS version has been 
> reported to work (a few days ago) with PGI and 64-bit executables:
> you need to define -D__LINUX64
> 
> Paolo
>