1. 22 Sep, 2017 3 commits
    • Henry Weller's avatar
      fileOperation: Corrected processor counting for moving mesh cases · 18874f00
      Henry Weller authored and Andrew Heather's avatar Andrew Heather committed
      18874f00
    • Henry Weller's avatar
      argList: addition of fileHandler option moved to argList.C · a0692de3
      Henry Weller authored and Andrew Heather's avatar Andrew Heather committed
      Patch contributed by Timo Niemi, VTT.
      Resolves bug-report https://bugs.openfoam.org/view.php?id=2645
      a0692de3
    • Andrew Heather's avatar
      INT: Integration of Mattijs' collocated parallel IO additions · 85f12ff5
      Andrew Heather authored
      Original commit message:
      ------------------------
      
      Parallel IO: New collated file format
      
      When an OpenFOAM simulation runs in parallel, the data for decomposed fields and
      mesh(es) has historically been stored in multiple files within separate
      directories for each processor.  Processor directories are named 'processorN',
      where N is the processor number.
      
      This commit introduces an alternative "collated" file format where the data for
      each decomposed field (and mesh) is collated into a single file, which is
      written and read on the master processor.  The files are stored in a single
      directory named 'processors'.
      
      The new format produces significantly fewer files - one per field, instead of N
      per field.  For large parallel cases, this avoids the restriction on the number
      of open files imposed by the operating system limits.
      
      The file writing can be threaded allowing the simulation to continue running
      while the data is being written to file.  NFS (Network File System) is not
      needed when using the the collated format and additionally, there is an option
      to run without NFS with the original uncollated approach, known as
      "masterUncollated".
      
      The controls for the file handling are in the OptimisationSwitches of
      etc/controlDict:
      
      OptimisationSwitches
      {
          ...
      
          //- Parallel IO file handler
          //  uncollated (default), collated or masterUncollated
          fileHandler uncollated;
      
          //- collated: thread buffer size for queued file writes.
          //  If set to 0 or not sufficient for the file size threading is not used.
          //  Default: 2e9
          maxThreadFileBufferSize 2e9;
      
          //- masterUncollated: non-blocking buffer size.
          //  If the file exceeds this buffer size scheduled transfer is used.
          //  Default: 2e9
          maxMasterFileBufferSize 2e9;
      }
      
      When using the collated file handling, memory is allocated for the data in the
      thread.  maxThreadFileBufferSize sets the maximum size of memory in bytes that
      is allocated.  If the data exceeds this size, the write does not use threading.
      
      When using the masterUncollated file handling, non-blocking MPI communication
      requires a sufficiently large memory buffer on the master node.
      maxMasterFileBufferSize sets the maximum size in bytes of the buffer.  If the
      data exceeds this size, the system uses scheduled communication.
      
      The installation defaults for the fileHandler choice, maxThreadFileBufferSize
      and maxMasterFileBufferSize (set in etc/controlDict) can be over-ridden within
      the case controlDict file, like other parameters.  Additionally the fileHandler
      can be set by:
      - the "-fileHandler" command line argument;
      - a FOAM_FILEHANDLER environment variable.
      
      A foamFormatConvert utility allows users to convert files between the collated
      and uncollated formats, e.g.
          mpirun -np 2 foamFormatConvert -parallel -fileHandler uncollated
      
      An example case demonstrating the file handling methods is provided in:
      $FOAM_TUTORIALS/IO/fileHandling
      
      The work was undertaken by Mattijs Janssens, in collaboration with Henry Weller.
      85f12ff5