From: swlee <swlee@white.ce.kyungpook.ac.kr>
Newsgroups: comp.parallel.mpi
Subject: MPI_Prove v.s. nonProve
Date: Tue, 29 Dec 1998 11:45:29 +0900
Organization: System Engineering Research Institute (SERI)
Message-Id: <36884249.BA31C6F1@white.ce.kyungpook.ac.kr>
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I have experienced performance degrade of my program on MPICH.
the degrade is caused by MPI_Prove.
if  MPI_Prove and Get_count is executed before MPI_Receive ,
performance is degraded than otherwise.

    MPI_Probe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
    MPI_Get_count(&status, MPI_UNSIGNED_CHAR,&count);
    MPI_Recv(buf,  nMsg, MPI_CHAR, 1,  TAG,   MPI_COMM_WORLD,  &status);

My experimental result is created on SP2 and MPICH.
The program send Message and Receive between two process.
The message size is nMsg(16, 32, 64, ....).

nonProve version.
  0:Msg Size : 16, Avg time: 0.000466 , Max time: 0.000734
  0:Msg Size : 32, Avg time: 0.000467 , Max time: 0.000631
  0:Msg Size : 64, Avg time: 0.000468 , Max time: 0.000652
  0:Msg Size : 128, Avg time: 0.000487 , Max time: 0.000693
  0:Msg Size : 256, Avg time: 0.000584 , Max time: 0.000774
  0:Msg Size : 512, Avg time: 0.000667 , Max time: 0.005365
  0:Msg Size : 1024, Avg time: 0.000685 , Max time: 0.001098

Prove Version
 0:Msg Size : 16, Avg time: 0.000529 , Max time: 0.003057
  0:Msg Size : 32, Avg time: 0.000539 , Max time: 0.004594
  0:Msg Size : 64, Avg time: 0.000530 , Max time: 0.002924
  0:Msg Size : 128, Avg time: 0.000557 , Max time: 0.004775
  0:Msg Size : 256, Avg time: 0.000693 , Max time: 0.005067
  0:Msg Size : 512, Avg time: 0.000713 , Max time: 0.007361
  0:Msg Size : 1024, Avg time: 0.000767 , Max time: 0.004839

Whenever executed, the result is different.
the smaller size message's transfer time is longer than the lager size
in the same version.
But nonProve version is faster by 0.0001sec than Prove version.
I wonder Prove function's degrade.
Who do you tell me the cause????

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檜 撩辦
Lee Sung-Woo
KyungPook National University
Department of Computer Engineering
Taegu 702-701, Korea
E-Mail : swlee@white.ce.kyungpook.ac.kr
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