Parallel HYCOM Development and Dataset Presentation via the Web

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Parallel HYCOM Development and Dataset
Presentation via the Web

• Matthew Rundquist, Bryan Schleck, Max Smirnoff,
  Laurie Miller, and Matthew OKeefe
• Department of Electrical and Computer Engineering
• and
• Parallel Computer Systems Laboratory
• University of Minnesota
• Minneapolis, Minnesota

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Method Used For Portability

• OPEN-MP with MPI
• OPEN-MP is a collection of compiler directives,
  library routines, and environment variables used
  to specify shared memory parallelism
• Used the same MPI structure as SC-MICOM
• OPEN-MP allows variables to be declared as
  private

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Timeline

• May 2000 - switched from trying to port with
  pthreads to OPEN-MP
• values computed were incorrect using pthreads
• Summer 2000 - trial and error of new
  synchronization methods on LINUX
• September 2000 - OPEN-MP MICOM successfully ran
  on LINUX but not SGI

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Timeline Continued

• October 2000 - visited Dr. Alan Wallcraft
• Dr. Wallcraft found errors that our LINUX boxes
  ignored
• Dr. Wallcraft helped us understand MPI in
  SC-MICOM in order for us to know whether or not
  MPI was working in OPEN-MP MICOM
• Present - incorporated Dr. Wallcrafts ideas into
  OPEN-MP MICOM and successfully ran it on LINUX
  and SGI

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OPEN-MP Structure

• Created one large parallel region that starts
  with the call to micom_glob and ends after the
  return from micom_glob
• Replaced thread_sync calls with OPEN-MP Barrier
  command(! OMP BARRIER)
• Replaced the psem and vsem calls with OPEN-MP
  lock and unlock calls

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Problem Files

• main.f - replaced sproc call with OPEN-MP
  parallel region
• micom_glob.f - replaced thread_sync calls with
  OPEN-MP Barrier commands
• threadit.f - thread synchronization in SC-MICOM
  used IRIX specific commands
• created an OPEN-MP locking scheme that properly
  synchronized the iothread thread with the worker
  thread(s) in the same fashion that the psem and
  vsem calls did in SC-MICOM

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Problem Files Continued

• csupport.c - searched for all IRIX specific
  commands and then replaced them with platform
  independent code
• any routines that needed to be atomic were
  replaced by OPEN-MP atomic blocks
• ctiming.c - SC-MICOM contains a block of code for
  SGI machines and a separate block for all other
  platforms
• timing calculations are not accurate for the
  non-SGI platforms

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OPEN-MP MICOM Status

• Runs on SGI and LINUX at the same runtime as
  SC-MICOM for one box with a worker thread and an
  iothread
• Running on SGI with mpirun -np 2 scales the same
  as SC-MICOM
• Still working on scaling via mpi on LINUX
• Ran a compare script between SC-MICOM and OPEN-MP
  MICOM and found that the data compared was the
  same

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Future Work on Parallel HYCOM

• Incorporation of HYCOM code into SC-MICOM, to
  create SC-HYCOM
• Complete ports to Digital UNIX, Alpha Linux, IBM
  SP, and Cray T3E
• Test runs on multiple processor machines such as
  the IBM-SP and an ALPHA Linux machine
• Test runs on multiple node clusters
• i.e., two 2 processor LINUX boxes versus two 2
  processor SGI boxes
• Performance tuning of all the above

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HYCOM Movies on the Web
Online Distribution of Ocean Simulations

• Java applets provide user interface
• Perl scripts create data in the background
• Three different Java applets planned
• Creation of subsets of raw data
• Rendering of still images or movies
• Cross-sections, point tracking, other (t.b.d.)
• User can specify which data fields appear in
  movies, subsets,etc..

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Current Efforts

• Data subset applet is finished
• User can get a subset of layered and
  non-layered data,
• and specify which layers (1-16) to include
• C programs are provided to generate images and
  floating
• point data from subsets.
• Movie applet is almost finished
• Currently generates movies of entire Atlantic
  ocean
• User specifies which variables and layers to
  include
• Future additions
• User will select any subset of the ocean
• Generate MPEG movies instead of animated .gif
• Applet for cross-sections, point tracking, etc
  is in design stage

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