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Subject: [OMPI users] Regarding the execution time calculation
From: seshendra seshu (seshu199_at_[hidden])
Date: 2012-05-03 07:48:56

I have written an parallel program and when i run my program on 4,8,16
nodes and calculated the execution time at master using MPI_Wtime in master
node. The problem the execution time is increasing rapidly like NON
parallel program-55 sec, and for parallel program 2-nodes--60sec , 4-nodes
74sec, 8-node--120 sec and for 16 nodes---for 180 sec. can i know my
problem in parallel version actually the time needs to be decreased but it
is increasing i dont the reason. i have calculated my time as shown below

double start,end;
start= MPI_Wtime;
// done some work
// start send from master node and receiving it
end =MPI_Wtime;
cout<<"execution time"<<end-start;
//in slave nodes done some work

Please help me in solving this problem.