6,726 questions
Score of -1
0 answers
90 views
NaN output of a multi-loop fortran+OpenMP code
In the following code, ekk, vkk, and tau are read from external files and stored as arrays. The code works fine serially but in parallel gives NaN for all the tot_delta. I would appreciate any hints ...
- reputation score 1
Advice
1
vote
4
replies
134
views
In Fortran, what is a short working example of parallel programming with communicating threads?
(UPDATE: I found one answer, see code at end)
Fortran has native built-in parallel features. I'm trying to use them in a program that does a search for a solution.
program do_co
implicit none
real(...
- reputation score 127
Advice
0
votes
1
replies
106
views
Can OpenMP be offloaded to Adreno GPU on ARM64 hardware?
GCC documentation is rather clear that the only GPUs supported for OpenMP offload are AMD and Nvidia.
LLVM documentation states Clang supports OpenMP target offloading to several different ...
- reputation score 8814
Score of 0
0 answers
99 views
Finding proper BLAS and OpenMP for Intel compilers with CMake
I have project in both C and Fortran built with CMake. This project requires standard stuff like BLAS, Lapack and OpenMP. This is the snippet that I use to find the packages and it works great with ...
- reputation score 33
Advice
2
votes
3
replies
83
views
Does a masked region have to be in an explicit parallel region?
This is an odd OpenMP question triggered by a possible compiler bug (?) we are chasing down. For a long time, we've had code that had:
!$omp masked
...
!$omp end masked
that didn't have an explicit ...
- reputation score 525
Advice
0
votes
2
replies
111
views
Is calling `omp_pause_resource` allowed after forking (v.s. before forking)?
I have a question on what is technically allowed by the omp standard when it comes to relinquish resources (using omp_pause_resource) with forking.
I understand that in section 12.12, pause_resource.1....
- reputation score 41
Advice
0
votes
0
replies
25
views
Is lastprivate on nested loop indices valid without a COLLAPSE clause?
For the flang implementation of OpenMP, we are discussing the following program. At issue is whether e.g. ii, iii, and iiii should be consider private or lastprivate, and if the former, whether the ...
- reputation score 905
Advice
0
votes
2
replies
78
views
OpenMP 5.2 declare simd with linear(p: ref) inconsistency between specification and example?
I'm seeking opinions on what appears to be an inconsistency between the OpenMP 5.2 specification and an official example regarding the declare simd directive with the linear(p: ref) clause.
1. The ...
- reputation score 1
Score of 2
2 answers
121 views
OMP_DYNAMIC and scaling experiments
When conducting scaling experiments on a code accelerated with OpenMP, is it standard practice to set OMP_DYNAMIC to false so that the number of threads spawned per parallel region is deterministic?
I ...
- reputation score 790
Best practices
0
votes
3
replies
110
views
Passive-container sieve: computing prime coordinates on a mod-60 grid rather than walking segments
I've implemented a prime sieve where segments are passive containers rather than active search spaces. Instead of walking through each segment to mark multiples, a function (ricerca_ciclo) computes ...
- reputation score 1
Advice
2
votes
6
replies
99
views
C++ containers and omp parallel
So I have an algorithm that gets a set of objects and computes a next set of objects. The code below is a toy version of the real code for brevity. The next snip illustrates the theme of the program ...
- reputation score 4525
Score of 1
0 answers
113 views
What is the difference between the values obtained from sched_getcpu() and getcpu(int*, int*) from sched.h?
Here is a minimal working c++ example to show what I mean:
#include <sched.h>
#include <iostream>
#include <sstream>
#include <omp.h>
int main(int argc, char** argv) {
#pragma ...
- reputation score 71
Score of 1
2 answers
237 views
How to recognize the main thread in an OpenMP program?
OpenMP uses its own scheme for numbering threads staring from 0 for the master thread. A master thread is the thread that initiated a parallel region, which is the main program thread in the following ...
- reputation score 24434
Score of 2
1 answer
180 views
How is a non-parallelized for loop inside an OpenMP parallel section executed?
Consider the following code:
#pragma omp parallel
for (int run = 0; run < 10; run++)
{
std::vector<int> out;
#pragma omp for
for (int i = 0; i < 1'000'000; i++)
{
...
}
}
...
- reputation score 7525
Best practices
0
votes
3
replies
109
views
Code design conundrum: runtime polymorphism, templates, compile times, and OpenMP
I'm struggling to finalise the design of my C++17 library.
One of the primary goals is to use runtime polymorphism to allow users to extend or rewrite default features of the library for their own use ...
- reputation score 308
