AVX2 with ICC 17 pdb2gmx regressiontests fail
It fails with:
Index Reference This test Error Description 48 -4724.69 -4490.64 0.0253977 6pti.pdb with charmm27 using vsite=none and water=tips3p
Occurs with 17u4 and 17u5 (haven't tested earlier updates). Doesn't seem to happen with 18u1. Also it is fine with without optimization (-DCMAKE_BUILD_TYPE=Debug).
cmake command line used (doesn't seem to depend on any specific flags):
FLAGS="-g";CFLAGS=$FLAGS CXXFLAGS=$FLAGS CC=icc CXX=icpc cmake3 .. -DGMX_FFT_LIBRARY=mkl -GNinja
Tested that the problem occurs in the mdrun step of the test (and not pdb2gmx, editconf, grompp). If I take the tpr file generated with a working version I get the same energy with the failing version.
I'll spend time to try to figure out whether this is a GROMACS bug, a compiler bug, or a too tight test. But any help would be greatly appreciated.
#2 Updated by Roland Schulz over 2 years ago
It doesn't happen with <=4 (t)MPI. Thus if compiled with GMX_MPI=on one needs to run gmxtest.pl with "-np 4" or bigger. If compiled without GMX_MPI (thus tmpi) then it should always appear (if machine has >=4 cores) because the -nt option of gmxtest.pl is ignored for the pdb2gmx test.