crollinson
commented
9 years ago Hey @DanielNScott . SMP with the Hybrid Integrator has been working fantastically for me. I completed a set of my 12000 yr runs at 6 northeastern sites over the weekend (~48 hrs at DTLSM = 900) and had one stability interruption that then went through just fine when I dropped DTLSM from 900 to 600 (15 min to 10).
I'm redoing them with the version from yesterday's updated pull request just to double check, but the numbers I got from the first run and the spin I just finished look completely reasonable based on quick glances at snapshots (no thorough analysis yet).
rgknox
apourmok
Hi All,
I put the Shared Memory Parallelism commits on the master. This will allow for the splitting of radiation scattering, photosynthesis and thermodynamics of different patches to different CPU cores.
This has been tested using RK4 and Hybrid integration This has had limited testing on gridded runs This has had no testing on coupled runs (but I don't suspect any breakage).
If you don't want to use shared memory, just keep doing what you have done in the past and nothing should change.
If you do want to use it, follow these steps for a single polygon run:
1) compile code with shared memory directives, if you are using OpenMP, the flag is '-fopenmp' 2) (optional) increase your stack size. On linux: "ulimit -s unlimited" 3) set run-time environment variables. If you are using OpenMP, the key variable is OMP_NUM_THREADS. This defines how many shared memory cores will be used. On linux: "export OMP_NUM_THREADS=X" where X is the number of cores you wish to use. REMEMBER: These cores must share RAM, so you are limited by the number of cores that are on one node. 4) Execute the simulation as you would normally.
This release is experimental for the time being. If you have trouble or crashes or poor reproducability of previous work, revert to commit 2a5d68ebb291581c932a442e2701e553b24b1170
ie:
git checkout 2a5d68ebb291581c932a442e2701e553b24b1170