Search found 28 matches

by Oldboy
Wed Nov 27, 2019 3:11 am
Forum: Using OpenMP
Topic: Travelling salesman problem in Open MP
Replies: 2
Views: 2137

Re: Travelling salesman problem in Open MP

Thank you Mark!

This Boruvka version of TSP works better:
https://github.com/dimitris21gr/Boruvka ... MP_boruvka

A "small" misstake must be corrected parralel -> parallel in the c-code.
by Oldboy
Thu Nov 14, 2019 3:50 am
Forum: Using OpenMP
Topic: Travelling salesman problem in Open MP
Replies: 2
Views: 2137

Travelling salesman problem in Open MP

I have found this link:
https://github.com/abhishek510/tsp_openmp

Something is wrong as the speedup is very small from 1 to 4 threads and none at all at 16 threads.
by Oldboy
Wed Nov 07, 2018 12:30 pm
Forum: Using OpenMP
Topic: omp parallel for loop, on map stl c++
Replies: 5
Views: 2275

Re: omp parallel for loop, on map stl c++

Take a look at this code:
http://people.sc.fsu.edu/~jburkardt/c_s ... a_openmp.c
It is very hard to win anything with few nodes (in this case 6).
Even with 60 nodes the open mp effect is small.
by Oldboy
Fri Aug 31, 2018 3:45 am
Forum: Using OpenMP
Topic: #pragma omp for simd not vectorization?
Replies: 2
Views: 1428

Re: #pragma omp for simd not vectorization?

If you have an Intel the effect of -mavx in GCC is very clear on the code.
My i7-8700 was around 100% faster with -mavx.
by Oldboy
Mon Sep 11, 2017 11:08 am
Forum: Using OpenMP
Topic: Satisfy in Open Mp
Replies: 4
Views: 2645

Re: Satisfy in Open Mp

Thank you Mark! Florida is in trouble now so here is the c-code I use gcc compiler in my tests. The -O3 has no effect except on the speed. # include <stdlib.h> # include <stdio.h> # include <time.h> # include <omp.h> int main ( int argc, char *argv[] ); int circuit_value ( int n, int bvec[] ); void ...
by Oldboy
Sat Sep 09, 2017 6:48 am
Forum: Using OpenMP
Topic: Satisfy in Open Mp
Replies: 4
Views: 2645

Re: Satisfy in Open Mp

Raspberry Pi is limited to 4 threads and it works well with satisfy and Openmp. But 3 threads are not very fast.... Satisfy 23 (15 solutions) 1 thread 1.12 sec 2 threads 0.58 sec 3 threads 0.38 sec 4 threads 0.35 sec Satisfy 27 (26 solutions) 1 thread 20.29sec 2 threads 10.28 sec 3 threads 11.48 sec...
by Oldboy
Sat Sep 09, 2017 5:42 am
Forum: Using OpenMP
Topic: Satisfy in Open Mp
Replies: 4
Views: 2645

Satisfy in Open Mp

http://people.sc.fsu.edu/~jburkardt/c_src/satisfy_openmp/satisfy_openmp.html Satisfy is available in Serial and Open Mp versions for C, C++, Fortran 77 and 90. The inputs are normally 23 but it should be no problem to increase this to something like 24-30 in order to get longer times (and better sc...
by Oldboy
Mon Dec 05, 2016 12:33 pm
Forum: Using OpenMP
Topic: OpenMP performance on Xeon vs Intel
Replies: 6
Views: 2816

Re: OpenMP performance on Xeon vs Intel

This could be restricted by OS: http://superuser.com/questions/495105/how-many-physical-processors-does-windows-8-support Not all versions of Windows is supporting two sockets (could be some restrictions in Linux too). Here you have some examples with Linux Enterprise version working fine: http://sp...
by Oldboy
Tue Apr 12, 2016 12:00 am
Forum: Using OpenMP
Topic: Unexpected degradation in Performance with diff workstation
Replies: 2
Views: 3979

Re: Unexpected degradation in Performance with diff workstat

We have not seen your code but there is often a limitation regarding cache and memory. If you take a look at this code: https://people.sc.fsu.edu/~jburkardt/cpp_src/md_openmp/md_openmp.html np=1000 (particles) With my 8 core AMD it scales well from 2 threads to 4 threads but not so well from 4 cores...