Benchmarking Results as of Jan 2023
- Hermit=True is ~50% quicker than Hermit=False in FMChain example (it's not easy to test with the BiFeO3 as Hermit=True doesn't work in the supercell).
- Using .mex will dramatically speed up the code (in the FMchain example it sped up the code by a factor of ~4 for all optmem and using .mex on BiFeO3 incommensurate calc. (no supercell) sped up the calculation by factor ~2)
- For many q-points (e.g. the FMChain) there is a bottle neck relating to matrix multiplication done in a loop over q-points (the matrices being multiplied depend on hemit = true/false but in both instances is responsible for >70% of the execution time)
- For many magnetic atoms the bottleneck is diagonalising a 2nmag x 2*nmag matrix (where nmag is the number of mag atoms in the supercell if present- not the structural unit cell) for each q-point. This diagonalisation takes ~ 60% of the execution time in the BiFeO3 examples when using the mex version (calls
eig_omp).This bottleneck doesn't necessarily scale linearly with the number of q-points because there is a .mex file that does a loop over a chunk of q-points, the size of the chunk is determined by the optmem argument - but in principle this could also be a bottlneck in systems with more modest nmag but a large number of q-points (e.g. in the FMChain example with mex not enabled this takes ~80% of the execution time).
- There are a handful of other matrix multiplication operations that each account for (2-5% of the execution time) that could be improved by using mex function sw_mtimesx if mex is enabled. For example
Tests produce a number of .txt files that summaries the execution time of spinwave (and possibly other functions). In general each test will perform a claculation with different input parameters - the results for different input parameters are saved in separate directories named as so TestName_param_1_value1_param2_value2 (e.g. FMchain_mex_0_hermit_0_optmem_10). Note that boolean values are cast to int (e.g. True = 1). A single test with the same set of parameters is often run multiple times with the reuslts saved in a separate numbered sub-directory that increments (01, 02 etc.). A test can be run with the MATLAB profiling enabled, in which case .html files will be saved that contains the time spent on each line of every .m file called (one file per .m file and a summary). In addiiton to profile results there are tic/toc timings that are saved to files with filenames tictoc_times_profile_0.txt - where the last number represents a bool True/False.
The tic/toc timings over multiple test runs can be averaged by calling average_profile_timings.m.