[mpich-discuss] MPI I/O SLOW- possible conflictingwithcommunication....code stuck for ever during IO

[Bruce Wu]

Sorry, I don't know what do you mean?

Do you have  error mail?
  ----- Original Message ----- 
  From: Rajeev Thakur 
  To: mpich-discuss at mcs.anl.gov 
  Sent: Monday, March 15, 2010 1:30 PM
  Subject: Re: [mpich-discuss] MPI I/O SLOW- possible conflictingwithcommunication....code stuck for ever during IO


  Can you send us a small test program that fails?



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    From: mpich-discuss-bounces at mcs.anl.gov [mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of hossam
    Sent: Sunday, March 14, 2010 1:57 PM
    To: mpich-discuss at mcs.anl.gov
    Subject: [mpich-discuss] MPI I/O SLOW- possible conflicting withcommunication....code stuck for ever during IO


    Hi,

    I think i have a well defined problem i wonder if someone can give an advice.

    I am running an MPI code (MPICH2) on a linux cluster. 

    When i run the code with no IO inside the main runtime loop. It works perfectly fine on any number of processors and nodes. When i start dumping data during the loop
    the code get stuck for ever after the second or third file. 

    Everything works perfectly fine on a single processor though.

    Now, to make things clearer: When i use ROMIO (MPI IO) it got stuck during opining the file (MPI_FILE_OPEN). 

    However, i tried regular open(....) at the root processor and then reducing the data to the root processor and write there. The code got stuck at the MPI_REDUCE call.

    If i eliminated all the processors communication and just do dump IO (both ways), it runs fine but it slows down significantly when dumping the data.

    I tried on three different clusters(all linux) and i got the same problem.

    I don't want say what i think is the problem, i don't really know, but if the experts here can help i will appreciate.

     Thanks


    On Sun, Mar 14, 2010 at 12:50 PM, hossam <hossam.elasrag at gmail.com> wrote:

      Hi,

      This is my first post to the mpi-forum. I have a runtime problem related to MPI using MPICH2. I wonder if this is the correct forum to post my problem.
      Please let me know so i can proceed forward with my problem details.

      Thanks












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