[gmx-developers] threads are now ON by default

[Sander Pronk]

Now that the last issues have been resolved with the threading code, thread-based parallelization has been turned on by default. To disable all the threading code, use

--disable-threads. 

in configure, or turn the option GMX_THREADS off with ccmake. 

Running mdrun with just one thread (the default) is almost exactly the same as running it without threading code: the only thing that's different is that the few remaining global variables are protected by mutexes.

Performance-wise mdrun runs very slightly faster with threads than with OpenMPI when Nthreads<=Ncores (and there is no other processes on the computer). When Nthreads>Ncores (or other processes are running), the thread code is much faster than OpenMPI, but the total runtime is still smaller than when Nthreads==Ncores.

If there's any problems in getting things running, or with performance, I'd very much like to hear about it.

Sander