The only thing that matters is that it's small enough. It overhead should be so small that it does not discourage users (developers) from putting it into the code (except for at the very low level).
If there are technical reasons for using boost::cpu_timer, then I guess it's ok. -- Anders mån 30 mars 2015 kl 15:13 skrev Jan Blechta <[email protected]>: > On Mon, 30 Mar 2015 13:55:55 +0200 > Jan Blechta <[email protected]> wrote: > > > On Mon, 30 Mar 2015 11:34:19 +0000 > > Anders Logg <[email protected]> wrote: > > > > > See this question on the QA forum: > > > > > > http://fenicsproject.org/qa/6875/ubuntu-compile-from- > source-which-provide-better-performance > > > > > > The Cahn-Hilliard demo takes 40 seconds with 1.3 Ubuntu packages and > > > 52 seconds with 1.5+ built from source. Are these regressions in > > > performance or is Johannes that much better at building Debian > > > packages than I am building FEniCS (with HashDist). > > > > > > PS: Looking at the benchbot, there seem to have been some > > > regressions in the timing facilities with the recent changes: > > > > Ok, I will look if something can be done with common-timing-cpp > > regression. I have a guess what causes that. > > I haven't profiled it rigorously yet but it seems that most of the > regression is due to switching from gettimeofday() from sys/time.h to > boost::cpu_timer. > > Anders, is there any strong reason for improving the current timings? > Isn't it fast enough? I don't think that we use Timer class in any loop > such tight that this slowddown would have effect and I would hardly > expect users doing it. > > Jan > > > > > Nevertheless, please note slowdown of la-vector-access-cpp. > > http://fenicsproject.org/benchbot/la-vector-access-cpp_ > last_five_years.png > > > > It could be a cause of the regression of Cahn-Hilliard demo. You could > > even try running it with uBLAS/UmfpackLUSolver on both versions to see > > whether the problem is in PETSc/wrappers. > > > > Jan > > > > > > > > http://fenicsproject.org/benchbot/ > > > > > > -- > > > Anders > > > > _______________________________________________ > > fenics mailing list > > [email protected] > > http://fenicsproject.org/mailman/listinfo/fenics > >
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