[Carpet] CarpetIOAscii and .d.asc files

[Erik Schnetter]

On Mar 5, 2008, at 17:49:23, Yosef Zlochower wrote:

> Erik Schnetter wrote:
>> On Mar 5, 2008, at 16:58:08, Yosef Zlochower wrote:
>>> Hi Erik,
>>>
>>> While testing the development version of carpet I noticed that
>>> the .d.asc files where vastly larger than the .[xyz].asc files.
>>> I checked and most of the lines in the .d.asc files are actually  
>>> lines
>>> containing only '#'
>>>
>>> $ grep "#" gxx.d.asc  | wc -l
>>> 81254538
>>> $ cat gxx.d.asc  | wc -l
>>> 81260186
>>>
>>> I don't see anything similar for the stable version.
>>> I ran the parfile given below on 4, 8, 12, 16, and 20 nodes
>>> (4 cores per node)
>> The logic for determining which processor owns a part of the  
>> diagonal is different than the logic for the  output along the  
>> diagonals.  Effectively each processor outputs its part of the  
>> diagonal -- and if a processor doesn't own a part of the diagonal,  
>> only the lines starting with "#" show up.
>> Can you confirm that this is correct?
>> ASCII I/O does not scale to many processors.  One could either  
>> write one file per processor, which has its own set of problems, or  
>> use HDF5 I/O instead.  It would be straightforward to implement 1D  
>> HDF5 I/O, plus a script to convert HDF5 to gnuplot format.  This  
>> would greatly reduce both output time and file size.
>> -erik
>
> but why is the .d file using 156 times as much disk space
> as the others?

Can you confirm that my suspicion that each processor outputs lines  
starting with "#" is correct?  If you look at the actual file, you  
should see in the lines starting with "#" from which processor they  
come.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/

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