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H__Kamil
Beginner
103 Views

OpenMP Accelerator Model - signal 11 (SIGSEGV)

Hello,

currently I am working with OpenMP Accelerator Model and I would like use OpenMP offload for executing my application on KNC coprocessor. In my application I use #omp target data region to ensuring data reusing. However, as a result, during execution of my application I get following error: offload error: process on the device 0 was terminated by signal 11 (SIGSEGV). I am trying to reslove my problem, but I don't know how to do it. The way in which I use OpenMP #target constructs in my application presents simple code bellow. 

#include <iostream>
#include <omp.h>
using namespace std;

int main()
{    
    const int size = 100000;
    double* A = (double*) _mm_malloc(size * sizeof (double), 64);
    double* B = (double*) _mm_malloc(size * sizeof (double), 64);
    double* C = (double*) _mm_malloc(size * sizeof (double), 64);
    
    for(int i=0; i<size; ++i)
    {
        A = B = i;
        C = 0.0;
    }
    
    
    #pragma omp target data map(to:A[0:size]) map(to:B[0:size]) map(to:C[0:size])
    {
        for(int ts=0; ts<100; ++ts)
        {
            #pragma omp target
            {
                #pragma omp parallel for
                for(int i=0; i<size; ++i)
                {
                    C = B * A;
                }
            }
        }
    }
    
    _mm_free(A);
    _mm_free(B);
    _mm_free(C);
    
    return 0;
}

I compile my code using icpc 17.0.1 with -O3 and -qopenmp flags. What can be problem, and how to reslove it?

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1 Reply
Rajiv_D_Intel
Employee
103 Views

You will need to add the same map clauses for A, B and C on the inner "omp target". That ensures that the pointers A, B, C are updated on the device.

Note that the actual data transfer of A, B and C is only done once, by the outer "target data"

 

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