On Sat, Apr 9, 2016 at 12:21 AM, Johannes Wagner <[email protected]> wrote: > hey all, > got a few questions for people with dual-gpu setups: > > - does anyone have tested and well performing explicit threading parameters > for a typical GPU compute node with 2 CPU's + HT and dual GPU? The automatic > settings for our hardware (2x8core cpu + HT & dual GPU) take 8MPI x 4OMP, > which I find odd. Did not start testing and playing around yet, wanted to ask > here before...
That's normal and the choice is the result of extensive testing which showed that typically narrower ranks (<=6 threads/rank is what the automation targets) are faster; there are additional benefits to multiple ranks sharing a GPU like transfer and kernel overlap. > > - for anyone using 980ti or Titan X cards, in a clear GPU limited case, whats > the maximum GPU utilization one can observe (e.g. using nvidia-smi)? Single rank 70-80%, with domain decomposition 60-70% is good. You will get less if the tasks outside the force compute region take time (e.g. constraints, update, pulling). > - for anyone using dual 980Ti or Titan X setups, what is the required CPU to > have a more or less balanced CPU/GPU utilization? Depends very much on the input, e.g. with AMBER shorter cutoffs are used hence there is less short-range work, while CHARMM requires longer cutoffs and use the slightly slower switch kernels. The two cards you list are quite fast, so they'll need fast CPUs and will balance well with 6-8 fast cores (e.g. i7 SBE CPUs) or 10+ lower clocked cores like those on Xeons. Given that you mention 2x8 Xeon cores, I can imagine that your runs aren't GPU-bound but are limited by the CPU. Cheers, -- Szilárd > thanks, Johannes > > -- > Gromacs Users mailing list > > * Please search the archive at > http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! > > * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists > > * For (un)subscribe requests visit > https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a > mail to [email protected]. -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to [email protected].
