On 12 September 2011 21:36, Marie E. Rognes <m...@simula.no> wrote: > On 09/12/11 20:00, Marie E. Rognes wrote: >> >> On 09/12/11 19:54, Garth N. Wells wrote: >>> >>> On 12 September 2011 18:49, Marie E. Rognes<m...@simula.no> wrote: >>>> >>>> On 09/12/11 19:40, Garth N. Wells wrote: >>>>> >>>>> Which compiler options did you use when evaluating the speed up? >>>>> >>>> Tested Extrapolation.h with vanilla dolfin (which is dominated by >>>> evaluate_basis calls). No additional compiler options set. >>>> >>>> What are the default compiler options? >>>> >>> '-g' for plain JIT, which is dead slow. You should test with at least: >>> >>> parameters["form_compiler"]["cpp_optimize"] = True >>> >>> in the Python code. This will use '-O2'.
Isn't this limited in a way? Would it be a problem to let users do: parameters["form_compiler"]["cpp_optimize"] = '-O2 -funroll-loops' parameters["form_compiler"]["cpp_optimize"] = '-O3' and then perhaps let parameters["form_compiler"]["cpp_optimize"] = True default to '-O2' as we do now? Just a thought. >> >> Ok, thanks -- I'll take a closer look. >> > > Take a look at the attached results in old_evaluate_basis.txt (results with > "old" FFC), > and new_evaluate_basis.txt (results with "new" FFC) from running the > attached > test_evaluate_basis.py. > > Acceptable? Looks good, and the generated code is much nicer now. :) It could have been fun to see the impact of the '-O2 -funroll-loops' option on the old code, but then you'll have to switch to C++. Anyway, I'm quite sure that the old code will never perform as well as the new code even with this option. As you have probably found out, the generated code was simply a mirror of what is going on in FIAT (translated to C++). Perhaps there are more places where we can simplify the generated code? Another thing in relation to improving the evaluate_basis* functions that I have thought about is if it's really necessary to support derivatives of arbitrary order. If we only generate code for the first derivative by default (and support arbitrary derivatives by a command line argument) the code will be a lot simpler (easier on C++ compiler) and much faster irrespective of which gcc optimisation is being used. Kristian > -- > Marie > > > > > > _______________________________________________ > Mailing list: https://launchpad.net/~ffc > Post to : ffc@lists.launchpad.net > Unsubscribe : https://launchpad.net/~ffc > More help : https://help.launchpad.net/ListHelp > > _______________________________________________ Mailing list: https://launchpad.net/~ffc Post to : ffc@lists.launchpad.net Unsubscribe : https://launchpad.net/~ffc More help : https://help.launchpad.net/ListHelp
