Parallel function calls

Accelerated Computing HPC Compilers Legacy PGI Compilers
1

Hello. I have the following code:

for(i=0;i<N;i++){
           function(i,B);
    }

where function (i,B) is this:

void function(i,B){
         for(j=0;j<N;j++){
         //Do calculations on B
   }
}

I want to make it parrallel using OpenAcc. Is making the function parallel alone is one thing. Is it possible to have parallel calls of the fuction?

2

Yes. You can do something like the following to accelerate the outer loop across the gangs and the loop within “function” across the vectors.

#pragma acc routine vector
void function(i,B){ 
#pragma acc loop vector
         for(j=0;j<N;j++){ 
         //Do calculations on B 
...

#pragma acc parallel loop gang
for(i=0;i<N;i++){ 
           function(i,B); 
    }
  • Mat