Subject: Re: [boost] [Parallel Algorithms] Queries regarding the Boost.Thread / Parallel algorithms
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2014-03-26 05:48:49
On 24/03/14 18:00, Naveen wrote:
> 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.
While this is a pretty bad implementation of matrix multiplication, it's
interesting because it involves multiple loops.
A good implementation would parallelize regardless of the number of
iterations in each loop, which are all set to 100 in your example but
which might be smaller in other cases.
> 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.
That's a basic skeleton for parallel_transform on an SMP machine.
> Please clarify, whether there are any alternative approaches available to
> achieve parallelism using threads.
There are plenty. Just look at the literature on the subject.