openmp

问题 test.fa.gz file contains multiple 4 lines as blow: @HWI-ST298:420:B08APABXX:3:1101:1244:2212 1:N:0:TCATTC GGCAAGGCACTTACTTTACAGCTAAAGAAGTGCAGC + @@@FDFFDFHCFDACGHC<<CCFEHHFCCFCEE:C? What I want to do is to read every four lines of *.fq.gz file in parallel with OpenMP. The code blow could be compiled successfully, but will show incorrect results sometimes. In each for loop, I used 4 times of getline() to read the file. I'm not sure how OpenMP will handle the multiple jobs in each for loop and

问题 I need to make t static to each thread, how can I do that? I tried this but t is not static private to each thread. #pragma omp Parallel { traceRays(); } ... ... void traceRays() { static float t = 1; } 回答1: if the static variable is not declared in the parallel region, then everytime you attempt to define in the parallel region use: #omp parallel private(t) 回答2: You can do it by just making t threadprivate: void traceRays() { static float t = 1; #pragma omp threadprivate(t) } 来源： https:/

问题 I'm trying to implement the compare and swap operation so that my threads know whether or not to enter a particular region based on a value u_parent . I just want to know if this is the correct way to implement it and if I am going wrong somewhere. int *u_parent; u_parent = &graph->parents[u]; if (*u_parent < 0) { // This region should only be entered by each thread // if the value of u_parent is < -1. graph->parents[u] = v; // ^-- If region is entered, this value is modified // by some

问题 I have been told not to use printf in openmp programs as it degrades the performance of parallel simulation program. I want to know what is the substitute for that. I mean how to display the output of a program without using printf. I have the following AES-128 simulation problem using openmp which needs further comments Parallel simulation of AES in C using Openmp I want to know how to output the cipher text without degrading the simulation performance? Thanks in advance. 回答1: You cannot

问题 This question already has answers here : Why Segmentation fault is happening in this openmp code? (2 answers) Closed 3 years ago . I am using Eclipse with GNU Fortran compiler to compute a large arrays to solve a matrix problem. However, I have read and notice that I am unable to read all my data into the array which causes my project.exe to crash when I invoke -fopenmp into my compiler settings; otherwise, the program works fine. program Top_tier integer, parameter:: n=145894, nz_num=4608168

问题 I have a FORTRAN program written for the parallel computing. The program takes the arguments and the number of threads can be defined as the argument. The sample code is as follows: COUNT = NARGS() NTHREADS = 1 ! *** GET THE COMMAND LINE ARGUMENTS, IF ANY IF(COUNT.GT.1)THEN ! *** ARGUMENT 1 CALL GETARG(1, BUFFER, iStatus) IF (Buffer(1:4).EQ.'-NOP'.OR.Buffer(1:4).EQ.'-nop') THEN PAUSEIT=.FALSE. ENDIF IF (Buffer(1:3).EQ.'-NT'.OR.Buffer(1:3).EQ.'-nt') THEN READ(Buffer(4:10),*) NTHREADS ENDIF IF

问题 I am trying to make my_class thread-safe like so. class my_class { const std::vector<double>& get_data() const { //lock so that cannot get_data() while setting data lock l(m_mutex); return m_data; } void run() { vector<double> tmp; //some calculations on tmp. { //lock so that cannot get_data() while setting m_data lock l(m_mutex); m_data = tmp; //set the data } } private: std::vector<double> m_data; mutex m_mutex; my_class(); //non-copyable } run() and get_data() may be called by different

问题 I would like to know a way to get the range of values for a given thread in a parallized for loop in OpenMP with C++. For example in the following code I would like to know what the first value each thread uses in the loop for each thread. #pragma omp parallel for schedule(static) for(int i=0; i<n; i++) Let me give you an example of why I might want these values. Let's assume I want to fill an array with the sum of the counting numbers. The closed form solution for the sum of the counting

问题 This question already has answers here : Why OpenMP under ubuntu 12.04 is slower than serial version (3 answers) Parallelizing matrix times a vector by columns and by rows with OpenMP (1 answer) Closed 5 years ago . I'm trying to write Matrix by vector multiplication in C (OpenMP) but my program slows when I add processors... 1 proc - 1,3 s 2 proc - 2,6 s 4 proc - 5,47 s I tested this on my PC (core i5) and our school's cluster and the result is the same (program slows) here is my code

问题 I am writing a cfd simulation and want to parallelise my ~10^5 loop (lattice size), which is part of a member function. The implementation of the openMp code is straight forward: I read entries of shared arrays, do calculations with thread-private quantities and finally write in a shared array again. In every array I only access the array element of the loop number, so I don't expect a race condition and I don't see any reason to flush. Testing the speedup of the code(the parallel part), I