[FLASH-USERS] Big Problem??

[Tomasz Plewa]

Although I prefer a low cost approach to debugging which avoids dealing 
with setup/system/compiler information at first and attempts to 
eliminate 99% of the source code, here are  quick comments on your systems.

(1) pgi 6.0 is a quite antique compiler. It's so old that now I do not 
even remember what problems we may have had with it. I suspect quite a 
few and none of them might be relevant...

(2) As you might noticed, intel has a newer compiler version. Your 
CentOS5 system needs upgrades on both mpich2 and compiler sides.

(3) Your Ubuntu system seems relatively up-to-date although HDF5 1.8.x 
is out there and seems working fine.

(4) Compilers are known to do strange things to perfect codes! So if you 
run into a trouble on a new system, one of the first things to try is to 
lower compiler optimization level. Avoiding -fast or -ip or -inline is 
usually a good idea. Simple -O0 may suffice for a couple of steps. As a 
bonus, the code compiles fast. Then the trick is to get it crashing 
quickly...

Again, I suggest to simplify your application, isolate the problem, fix 
it, then find the best compiler, mpich, options, etc., to run your 
production code.

Enjoy your weekend!

Tomek
--
Seyit Hocuk wrote:
> Hi Nathan,
> 
> Thats a good Idea, I'll start simple and test those first thing monday. 
> It's too late for me now.
> 
> To answer your questions:
> 
> The problem I am running is my own home made, actually it's a modified 
> version of Jeans. Basically including heat, cool, eos gamma, 
> compositions, adjusted refinement criteria similar to one of the other 
> problems (with delta_ref and delta_deref) and a scala of other small 
> things.
> 
> 1)
> Centos5
> Linux celsius 2.6.18-53.1.19.el5 #1 SMP Wed May 7 08:20:19 EDT 2008 i686 
> i686 i386 GNU/Linux
> ifort intel compiler version 8.0
> hdf5 1.6.6 (serial)
> mpich2 Version:  1.0.3
> gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)
> FFLAGS_OPT   =  -c -r8 -i4 -fast -ipo -ipo_obj  -I $(MPI_PATH)/include
> 
> 2)
> Debian (??)
> Linux hpcibm1 2.6.8-11-amd64-k8-smp #1 SMP Sun Oct 2 20:03:22 UTC 2005 
> x86_64 GNU/Linux
> pgf90 6.0-5 32-bit target on x86-64 Linux
> hdf5 1.4.5 (serial)
> mpich2 version 1.0.5
> gcc version 3.3.5 (Debian 1:3.3.5-13)
> FFLAGS_OPT = -c -fast -r8 -i4
> 
> 3)
> Ubuntu
> Linux si01 2.6.24.3 #1 SMP Fri Jul 4 11:02:09 CEST 2008 x86_64 GNU/Linux
> ifort intel compiler version 10.1.012
> hdf5 1.6.7 (serial)
> mpich2 Version: 1.0.6
> gcc version 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
> FFLAGS_OPT   = -c -r8 -i4  -xT -O3 -no-prec-div -static -I 
> $(MPI_PATH)/include
> or (only -ipo difference, result seemingly doesn't change)
> FFLAGS_OPT   = -c -r8 -i4  -fast -I $(MPI_PATH)/include
> 
> 
> 
> 
> Nathan Hearn wrote:
>> Hi Seyit,
>>
>>     Are you seeing these differences in the standard test problems
>> included in Flash (e.g., Noh, Sod, Sedov), or are they specific to the
>> problem that you are running.  (Really, this follows from Tomek's
>> advice to look at the simplest configurations where the differences
>> are seen.)
>>
>>     Also, it would be good to include some more information in your
>> messages, for instance: the problem that you are running, the specific
>> architectures and compilers, the optimization flags, and the library
>> versions for HDF5 and MPI that you are using.  Details like these can
>> be really helpful in evaluating and fixing the issues you are seeing.
>>
>>
>> - Nathan
>>
>>
>> On Fri, Jul 18, 2008 at 11:32 AM, Seyit Hocuk <seyit at astro.rug.nl> wrote:
>>  
>>> Oh man,
>>>
>>> I am using 3 different computers (with different architectures, 
>>> compilers,
>>> optimizations, environments). All three start differently immediately 
>>> from
>>> the beginning (difference in dt_hydro and refinement).
>>> Should I worry very very very much?
>>> I'm now doing a complete simulation and am going to check if my end 
>>> results
>>> also change.
>>>
>>> I'm trembling by the thought.....
>>>     
> 
> 

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