On Tue, May 2, 2017 at 9:48 PM, Roland Haas <[email protected]> wrote:
> Hello Robert, > > > My problem is similar to the one discussed in a thread here in April, > > though I have not solved it. My system is based on the AMD FX-8350 > > CPU, which should have either 4 or eight cores depending on whether > > they are physical or virtual. The OS is Ubuntu 17.04 Zesty Zapus > > (x64), released a couple of weeks ago. I followed the Simplified > > Tutorial, with everything pasted in without alteration. (The > > exception is that 'mpich' is apparently required instead of > > 'mpich2.') > Good to know. I'll update the tutorial, just have to understand how > to make it work with the LTS and current releases and ideally both 17 > and 16. > > > The graphical output is exactly the same as that presented > > on the Website, as near as I can tell. When computation starts, it > > says it's using one thread, instead of the same number as the number > > of processors, as I was led to believe. I then set the environment > > variable: export OMP_NUM_THREADS=4 and verified it with printenv, but > > it's still using only one thread. (It took about five hours to > Hmm, so given that printenv worked and showed the OMP_NUM_THREADS is > the expected value it should also show up in Carpet's output (and you > have eliminated ~75% of the usual causes). Can you attach the *.out > file, please? > > Given that you said you followed the simplified tutorial which uses > simfactory, OMP_NUM_THREADS is likely not respected since the > debian.run file overwrites it. Instead when using simfactory to > start the simulation did you specify a --num-threads option? Like so: > > simfactory/bin/sim submit static_tov --parfile par/static_tov.par > --procs 1 --num-threads 4 ? > > This may actually fail stating that there are not enough cores on you > laptop since simfactory (I think) defaults to assuming only a single > core. You may have to add "--mdbentry max-num-threads 4 --mdb-entry ppn > 4" as well. This should likely be changed in simfactory. > > Please do not use --procs 4 --num-threads 4 or similar since the number > of cores used with be --procs (number of processes) times --num-threads > (numer of threads per process) though that would give you a different > output in Carpet. > I'm not sure this is correct. I think that "procs" specifies the total number of cores that Cactus uses, and "num-threads" specifies the number of OpenMP threads per MPI process. The number of MPI processes is then the quotient of "procs" and "num-threads". Apart from this I agree with Roland that the *.out file will likely contain the information needed to debug this. -erik -- Erik Schnetter <[email protected]> http://www.perimeterinstitute.ca/personal/eschnetter/
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