[mpich-discuss] comparison of execution times:

[Rajeev Thakur]

It is possible that there is better cache utilization in the parallel
program than in the sequential one. As an experiment, run the sequential
program with only 250 iterations and see if the time is less than half
the time taken by the sequential program with 500 iterations.
 
Rajeev
 


  _____  

From: mpich-discuss-bounces at mcs.anl.gov
[mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of sankar s
Sent: Sunday, May 23, 2010 6:02 AM
To: mpich-discuss at mcs.anl.gov
Subject: [mpich-discuss] comparison of execution times:


Hi, 

I have done a simulation program in C, which contains 500 Replications.
In sequential code these 500 replications will be done one by one and
the combined results will be posted in output at last.

Same code I have written for MPI. first 250 replications in processor 0
and next 250 replications in processor 1. after completion of processor
0, it will send these results to processor 1. Processor 1 combines all
the results and gives the output.

I expected, because of doing these parallelism, the execution time of
MPI should be half or some what more than half than sequential code.

But parallel code is  taking less than half execution time of sequential
code. Some times (1/3rd also). Results point of view it is good. But I
don't understand why it is taking less than half time?

am using DELL  core2duo processor and windows 7 OS.


Thank you

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