parallel processing - fork-join algorithms with ompss -

openmp/ompss allows define tasks specific inputs , outputs dependencies among different tasks can defined.

most of examples feature different functions tasks connected each other via dependencies. standard parallel for-based program? possible define dependencies i.e. among iterations of consecutive 'parallel for' regions?

you don't need functions define dependencies.

let's take example non-commutative operation such concatenation, here inout dependency make sure tasks executed in order.

char buf_n[11] = {0}, buf_l[11] = {0}, buf_u[11] = {0}; #pragma omp parallel { #pragma omp single     {         int i;         (i=0; < 10; i++)         {  #pragma omp task depend(inout:buf_n) firstprivate(i)             {                 char add[] = {'0' + i};                 strncat(buf_n, add, 1);             }  #pragma omp task depend(inout:buf_l) firstprivate(i)             {                 char add[] = {'a' + i};                 strncat(buf_l, add, 1);             }  #pragma omp task depend(inout:buf_u) firstprivate(i)             {                 char add[] = {'a' + i};                 strncat(buf_u, add, 1);             }          }  #pragma omp task depend(in:buf_n)         {             printf("buf (numbers) %s\n", buf_n);         } #pragma omp task depend(in:buf_l)         {             printf("buf (lowercase) %s\n", buf_l);         } #pragma omp task depend(in:buf_u)         {             printf("buf (uppercase) %s\n", buf_u);         }     } } 

this return like:

buf (lowercase) abcdefghij buf (uppercase) abcdefghij buf (numbers) 0123456789 

the order of lines may change, concatenations happen in order (i.e. letters , numbers in right order).