openmp

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: The following code works based on the OpenMP 4.0 specification: The out and inout dependence-types. The generated task will be a dependent task of all previously generated sibling tasks that reference at least one of the list items in an in, out, or inout dependence-type list. This means that task3 becomes dependent of task2. Right? but it does not make sense! Why should an input-output dependency task be a dependent of an input dependency task? What do I need to do in order to make them independent? p.s: code tested with g++ 4.9 on Linux.

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have a program which distributes particles into a cloud-in-cell mesh. Simply loops over the total number of particles (Ntot) and populates a 256^3 mesh (i.e. each particle gets distributed over 8 cells). % gfortran -fopenmp cic.f90 -o ./cic Which compiles fine. But when I run it (./cic) I get a segmentation fault. I my looping is a classic omp do problem. The program works when I don't compile it in openmp. !$omp parallel do do i = 1,Ntot if (x1(i).gt.0.and.y1(i).gt.0.and.z1(i).gt.0) then dense(int(x1(i)),int(y1(i)),int(z1(i))) = dense(int

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am writing a C++ program that does a brute-force search for closed Knight's tours . The code is here . I would like to parallelize this using OpenMP. My problem is to do this in a way that creates a sufficient degree of parallelism. Currently the relevant portion of my code looks like this #pragma omp parallel for reduction(+:count) if (depth==4) for (size_t i=0;i The if (depth==4) is my attempt to make sure that not too many parallel tasks are created but on the other hand enough are created to keep all processors busy. Setting depth==2

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I'm trying to get openmp to run in my program on Mavericks, however when I try to compile using the flag -fopenmp I get the following error: ld : library not found for - lgomp clang : error : linker command failed with exit code 1 ( use - v to see invocation ) The command I am running is: gcc myProgram . cpp - fopenmp - o myProgram Also, when I run gcc I get Clang warnings which I find to be very strange. And looking into /usr/bin/gcc it does not appear to link to Clang. Any suggestions on how to fix my Clang errors and get openmp

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm playing around with locks and critical sections for making a loop thread safe. Here is the code: #pragma omp parallel for num_threads(4) private(k, f_part_k, len, len_3, mg, fact) for (k = part+1; k < n; k++) { /* Compute force on part due to k */ f_part_k[X] = curr[part].s[X] - curr[k].s[X]; f_part_k[Y] = curr[part].s[Y] - curr[k].s[Y]; len = sqrt(f_part_k[X]*f_part_k[X] + f_part_k[Y]*f_part_k[Y]); len_3 = len*len*len; mg = -G*curr[part].m*curr[k].m; fact = mg/len_3; f_part_k[X] *= fact; f_part_k[Y] *= fact; /* Add force in to total

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I have the following code that I want to parallelize: int ncip ( int dim , double R ) { int i ; int r = ( int ) floor ( R ); if ( dim == 1 ) { return 1 + 2 * r ; } int n = ncip ( dim - 1 , R ); // last coord 0 #pragma omp parallel for for ( i = 1 ; i <= r ; ++ i ) { n += 2 * ncip ( dim - 1 , sqrt ( R * R - i * i ) ); // last coord +- i } return n ; } The program execution time when ran without openmp is 6.956s when I try and parallelize the for loop my execution time is greater than 3 minutes (and that's because I ended it myself).

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I would like to run the following code (below). I want to spawn two independent threads, each one would run a parallel for loop. Unfortunately, I get an error. Apparently, parallel for cannot be spawned inside section . How to solve that? #include #include "stdio.h" int main () { omp_set_num_threads ( 10 ); #pragma omp parallel #pragma omp sections { #pragma omp section #pragma omp for for ( int i = 0 ; i < 5 ; i ++) { printf ( "x %d\n" , i ); } #pragma omp section #pragma omp for for ( int i = 0 ; i < 5 ; i ++) { printf ( ". %d\n"

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: In the default LLVM provided by Apple in macOS 10.13, High Sierra, is OpenMP finally available? It has been available in main LLVM for more than a year now. (another way to ask the question might be what version of LLVM is the new Apple LLVM based on) 回答1: Standard Apple's clang supports OpenMP. They just disabled the driver option. But you can use the frontend option instead this way: clang -Xclang -fopenmp -I -L -lomp Also, you need to set DYLD_LIBRARY_PATH environmental variable: export DYLD_LIBRARY_PATH= How to get/build libomp

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I am using Mac OS X Sierra, and I found that clang (LLVM version 8.1.0 (clang-802.0.38)) does not support OpenMP: when I run clang -fopenmp program_name.c , I got the following error: clang: error: unsupported option '-fopenmp' It seems that clang does not support -fopenmp flag. I could not find any openmp library in homebrew. According to LLVM website, LLVM already supports OpenMP. But I could not find a way to enable it during compiling. Does this mean that the default clang in Mac does not support OpenMP? Could you provide any

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have problems compiling OpenMP code using clang (both 3.6 and 3.8 ToT). I followed this blog post http://blog.llvm.org/2015/05/openmp-support_22.html , but the problem is that the compiled program is executed on a one thread only. I'm using ubuntu 15.04 x64, I have both libgomp and libiopmp installed and I compile my code with the following command: clang test.c -o test -fopenmp -L/usr/lib/gcc/x86_64-linux-gnu/5.1.1 When I use gcc instead, everything works fine: gcc test.c -o test -fopenmp I also tried running export LD_LIBRARY_PATH=/usr