openmp

问题 I need to make 4 teams with 4 threads each one with contiguous processors. The result I'm expecting is, for example: Team 0 Thread 0 Processor: 0 Team 0 Thread 1 Processor: 1 Team 0 Thread 2 Processor: 2 Team 0 Thread 3 Processor: 3 Team 1 Thread 0 Processor: 4 Team 1 Thread 1 Processor: 5 Team 1 Thread 2 Processor: 6 Team 1 Thread 3 Processor: 7 Team 2 Thread 0 Processor: 8 Team 2 Thread 1 Processor: 9 Team 2 Thread 2 Processor: 10 Team 2 Thread 3 Processor: 11 Team 3 Thread 0 Processor: 12

问题 I am wondering if I can parallelize this code using OpenMP. Will OpenMP make the code run faster? Is there a better way to achieve this? vector<int> t; // already initialized do{ // Something with current permutation } while(next_permutation(t.begin(), t.end())); I know I can easily parallelize a for instruction, but here I have a while (condition = true) . 回答1: next_permutation produces permutations in lexicographical order, which means that the prefixes to the permutations produced are also

问题 I have an OpenMP parallelized program that looks like that: [...] #pragma omp parallel { //initialize threads #pragma omp for for(...) { //Work is done here } } Now I'm adding MPI support. What I will need is a thread that handles the communication, in my case, calls GatherAll all the time and fills/empties a linked list for receiving/sending data from the other processes. That thread should send/receive until a flag is set. So right now there is no MPI stuff in the example, my question is

问题 I'm working with OpenMP in C++ and try to make a static member variable of a class threadprivate. A very simplified example code example looks like this #include <omp.h> #include<iostream> template<class numtype> class A { public: static numtype a; #pragma omp threadprivate(a) }; template<class numtype> numtype A<numtype>::a=1; int main() { #pragma omp parallel { A<int>::a = omp_get_thread_num(); #pragma omp critical { std::cout << A<int>::a << std::endl; } } /* end of parallel region */ } If

问题 I have a problem with terminating sections in a C program. After catching a SIGINT signal in one thread I wanted to exit all threads and I don't really know how because I have infinite loops in these loops. The program waits for input from server or stdin. So I used signal handler. I don't really know if I am doing this right way and I don't really understand how cancel in OpenMP works. I didn't find a proper tutorial or lecture for this. My task is after catching SIGINT signal, terminate the

问题 This is an update to my original question with a working code and runtimes included. I have a simple code that does a 2D random walk with multiple walkers over a number of steps. I'm trying to parallelize the walkers into group on each thread with openMP only on the inner loop. Here is the code. It outputs step number vs root mean square displacement (RMSD). The plot of Step vs RMSD should follow a power law with index around 0.5 as a check on the results (which it does). #include <stdio.h>

问题 So in my code there are various function that alter various arrays and the order in which the functions are called is important. As all functions are called a big number of times creating and destroying the threads has become a big overhead. EDIT on my question as I may have oversimplified my current problem. An example double ans = 0; for (int i = 0; i < 4000; i++){ funcA(a,b,c); funcB(a,b,c); ans = funcC(a,b,c): } prinft(ans); where funcA, funcB and func C are void funcA (int* a, point b,

问题 So in my code there are various function that alter various arrays and the order in which the functions are called is important. As all functions are called a big number of times creating and destroying the threads has become a big overhead. EDIT on my question as I may have oversimplified my current problem. An example double ans = 0; for (int i = 0; i < 4000; i++){ funcA(a,b,c); funcB(a,b,c); ans = funcC(a,b,c): } prinft(ans); where funcA, funcB and func C are void funcA (int* a, point b,

问题 I try to write a parallel for loop using openMP V.2.0. In the middle of the parallel region I construct an Object which I would like to be constructed once per thread. #pragma omp parallel for for (long i = 0; i < static_cast<long>(general_triangles.size()); ++i) { TrianglePointer tri = general_triangles[i]; if (tri.GetClassification() == TO_CLASSIFY) { bool tri_has_correct_normal = true; // --- Construct tree once per thread --- Tree tree(*(gp_boolean_operator->mp_group_manager)); if (tree

问题 i was expecting that variable "i" will reach a maximum value of 11 and then the "for" worksharing region will be cancelled ,code is: omp_set_num_threads(11); #pragma omp parallel { #pragma omp for for(i=0;i<9999;i++){ printf("%d by %d \n",i,omp_get_thread_num()); if(i>11) //2 { #pragma omp cancel for } }//for }//parallel omp pragma but the variable i was holding max value of 9998 which i suppose means that worksharing region was not cancelled. 回答1: Cancellation is disabled by default, mostly