The ABINIT Users Mailing List ( CLOSED )

["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

You are using gfortran.  That's at least what the output of configure says :
...
 
==============================================================================
 === Fortran support                                                        
===
 
==============================================================================

checking for f95... no
checking for fort... no
checking for xlf95... no
checking for ifc... no
checking for efc... no
checking for pgf95... no
checking for lf95... no
checking for gfortran... gfortran
checking whether we are using the GNU Fortran compiler... yes
...

Gfortran is the gnu fortran compiler. The main difference with some
other compilers is that you are free to correct any error you can find
within it. You are also free to use it and it comes bundled with most
linux (since it is only a frontend of gcc). Moreover the fact that it
is a mere parser for gcc internal language makes it remarquably
reliable. Just like g95.

The options "-static -O2 -march=native" are some options you can use
to make the code as fast as possible. "-static" ask for a static build
; that is one that do not require any external functions that has to
be loaded by your OS. The -O2 means optimisation level two. A pretty
equilibrated one. And "-march=native" tells the compiler that you want
the resulting binary to be optimized exclusively for the arch of your
own computer.

You will find much more documentation about the compiler in its own
manual. Try man (or info) on gcc, gfortran ...

regards

PMA

On Tue, Oct 21, 2008 at 4:47 PM,  <zhouy6@rpi.edu> wrote:
> Hi
>
> Thank you for you fast reply.
>
> I'm sure there is no other jobs running, so no confliction. I'll try 
> gfortran
> now to see what will happen.
>
> btw, what's difference between gfortran and other compilier? and what does "
> -static -march=native -O2" mean? I didn't find a comprehensive document in
> /abinit/docs.
>
> Thanks again!
>
> Yu Zhou
>
>
> On Tue, Oct 21, 2008 at 1:12 AM, Anglade Pierre-Matthieu <anglade@gmail.com>
> wrote:
>> Hi,
>>
>> That's just a little bit strange : your configure output tells that
>> the usual optimization for gfortran have been used. this should
>> provide a binary that is about 10% slower than the fastest possible
>> one in general.
>> 1) Are you sure no other task could have interfered with your benchmarking 
>> ?
>> 2) Does the other tests show the same discrepancy between your build
>> and the provided binary ? (for instance could you run and time "make
>> tests_acc") ?
>> 3) you could always try to enforce the compilation flags you want. For
>> instance you can try something like : ./configure FC="gfotran -static
>> -march=native -O2" .
>> regards
>>
>> PMA
>>
>



-- 
Pierre-Matthieu Anglade