dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Fri, Mar 12, 2010 at 06:58:22PM -0000, noreply@xxxxxxxxxxxxx wrote:
>> ------------------------------------------------------------
>> revno: 4635
>> committer: Garth N. Wells <gnw20@xxxxxxxxx>
>> branch nick: dolfin-all
>> timestamp: Fri 2010-03-12 18:53:05 +0000
>> message:
>>   Work on reading Vectors in parallel. Some issues to resolve still.
>>
>>   Some issues:
>>   - How should files be named when in parallel?
>>   - Should we have a 'master' xml file which points to the files
>>   - from different processes?
> 
> I think this should be done in the same way as for Meshes. We
> discussed the following design:
> 
> 1. Reading a single file "foo.xml" results in each process reading the
> entire file but skipping data located on another process as determined
> by local_range. This is what is implemented now for meshes (followed
> by communication and mesh partitioning). The difference for vectors
> would be that no extra communication is necessary.
> 

OK.

> 2. Reading a set of files "foo*.xml" results in each process reading
> its portion stored in "foo%d.xml" % p. The File interface then needs
> to check for the occurence of '*' and figure out the correct file name
> based on its process number.
> 

I think that are a number of advantages to having a single .xml that
points to the 'sub-files'. An obvious advantage is that we won't need to
distinguish between cases 1 and 2 when reading in a vector.

Garth

> Note that since all auxiliary parallel data is stored in MeshData, it
> should be possible to read in a mesh (stored in one file), partition
> it and then store it to "foo*.xml". Then restart the program and
> instead read the already partitioned data from the local file.
> 
> --
> Anders
> 
>