Re: [boost] [Parallel Algorithms] Queries regarding the Boost.Thread / Parallel algorithms

Subject: Re: [boost] [Parallel Algorithms] Queries regarding the Boost.Thread / Parallel algorithms
From: Naveen (nravichandrasekaran_at_[hidden])
Date: 2014-03-24 13:00:19

Hi,
In my previous mail, I was speaking about the compiler optimization
dependencies while creating a parallel version of the following code:

 DO J = 1, 100
    DO I = 1, 100
      DO K = 1, 100
         C(I,J) = C(I,J) + A(I,K) * B(K,J)
      END DO
    END DO
 END DO

As you know, the above code is the 2D-Matrix multiplication logic. I tested
the above logic using various compiler optimization levels from -o0, -o1,
-o2 and -o3. There were no problems due to the compiler optimizations. I
have used pthreads to convert the serial code to its parallel version.
Initially, the serial version took 72sec to execute and the parallel
version with 4 threads took around 16sec. Please have a look at the
attachment for the complete working source code.

The question now is, I have used the threads as shown in the pseudo code
below:

int main()
{
  create_pthreads(assign_thread_ID, call the function);

  join_threads(thread_ID);

  destroy_threads();
}

function_called_by_each_thread(thread_ID)
{
  all_computations;
}

All thread documentation reaches to some sort of options like this. Is this
the correct way to approach the problem for creating parallel algorithms
for boost threads.
Please clarify, whether there are any alternative approaches available to
achieve parallelism using threads.

PS: Please have a look at the code for further details

Regards,

*NAVEEN*
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