Hi, Affinity settings on the Talos II with Ubuntu 18.04 kernel 5.0 works fine. I get threads pinned where they should be (hwloc confirmed) and consistent results. I also get reasonable thread placement even without pinning (i.e. the kernel scatters first until #threads <= #hwthreads). I see only a minor penalty to not pinning -- not too surprising given that I have a single NUMA node and the kernel is doing its job.
Here are my quick the test results run on an 8-core Talos II Power9 + a GPU, using the adh_cubic input: $ grep Perf *.log test_1x1_rep1.log:Performance: 16.617 test_1x1_rep2.log:Performance: 16.479 test_1x1_rep3.log:Performance: 16.520 test_1x2_rep1.log:Performance: 32.034 test_1x2_rep2.log:Performance: 32.389 test_1x2_rep3.log:Performance: 32.340 test_1x4_rep1.log:Performance: 62.341 test_1x4_rep2.log:Performance: 62.569 test_1x4_rep3.log:Performance: 62.476 test_1x8_rep1.log:Performance: 97.049 test_1x8_rep2.log:Performance: 96.653 test_1x8_rep3.log:Performance: 96.889 This seems to point towards some issue with the OS or setup on the IBM machines you have -- and the unit test error may be one of the symptoms of it (as it suggests something is off with the hardware topology and a NUMA node is missing from it). I'd still suggest checking if a full not allocation with all threads, memory, etc passed to the job results in successful affinity settings i) in mdrun ii) in some other tool. Please update this thread if you have further findings. Cheers, -- Szilárd On Fri, Apr 24, 2020 at 10:52 PM Szilárd Páll <pall.szil...@gmail.com> wrote: > > The following lines are found in md.log for the POWER9/V100 run: >> >> Overriding thread affinity set outside gmx mdrun >> Pinning threads with an auto-selected logical core stride of 128 >> NOTE: Thread affinity was not set. >> >> The full md.log is available here: >> https://github.com/jdh4/running_gromacs/blob/master/03_benchmarks/md.log > > > I glanced over that at first, will see if I can reproduce it, though I > only have access to a Raptor Talos, not an IBM machine with Ubuntu. > > What OS are you using? > > > -- >> 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 gmx-users-requ...@gromacs.org. >> > -- 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 gmx-users-requ...@gromacs.org.