Issue
I am having issues with OpenMP and MPI execution timings. When I select either 4 Threads (OMP) or 4 Proccesses (MPI) my execution time is slower than the serial code.
Both scripts have correct timings on other machines and both use the gettimeofday() function for timing. Below is a screen shot of both scripts being executed from 1-8 Threads/Procs:
RAM is not exceeding its limit and the disk is not busy during execution.The machine hosts an Intel i5 2500k (Stock not overclocked) and is running on Linux Mint 17 x64.
AS mentioned before, both programs produce the correct timings on other machines, so I think the issue has something to do with cpu affinity and the OS.
Has anyone encountered this issue before?
EDIT 1:
When using the argument 'bind-to-core' on the MPI execution, runtime is significantly increased, but still much slower than serial:
Solution
Problem was faulty hardware.
I Replaced motherboard with one of the same series/chipset (so did not require an install) now the timings are returning correct on both scripts.
Answered By - Jamie Stuart Robin Parsons Answer Checked By - Candace Johnson (WPSolving Volunteer)