Sean, It's for performance reasons to prevent false sharing. This was a significant bottle neck in the v3 Mattes Mutual Information metric, so it was quite worth the effort.
Is this the cause for any failing tests? Or is this just a warning, that the alignment will be ignored? Here are some performance improvements number I posted to the developer's list for that patch: MeanSquares: Threads 3.2 4.2 4.2+patch patch percentage of 3.20 1 0.3615 0.8214 0.4071 113% 2 0.3222 0.6055 0.3365 104% 4 0.3249 0.4448 0.3293 101% 8 0.1703 0.3093 0.1943 114% 12 0.1457 0.2031 0.1322 91% 24* 0.1062 0.1332 0.0949 89% MutualInformation: Threads 3.2 4.2 4.2+patch patch percentage of 3.20 1 0.1467 0.6103 0.3353 228% 2 0.1036 0.3747 0.1774 171% 4 0.0847 0.2175 0.1262 149% 8 0.0655 0.1291 0.0681 104% 12 0.0551 0.1035 0.0486 88% 24* 0.0460 0.0829 0.0526 114% *Hyperthreading There is likely a better, and likely more complicated way to achieve the same results, which can not be done until after 4.4 release. I would object to hastily removing, this optimization. Brad On May 21, 2013, at 11:07 AM, Sean McBride <[email protected]> wrote: > Hi all, > > My Rogue7 dashboard has a few warnings from clang's -Wover-aligned: > > <http://open.cdash.org/viewBuildError.php?type=1&buildid=2911702> > > I'm not a language lawyer, but these look legit to me. Since I build as > C++11 I fall into: > > #define ITK_CACHE_LINE_ALIGNMENT 64 > > # define itkAlignedTypedef( alignment, oldtype, newtype ) \ > typedef oldtype newtype alignas(alignment) > > The standard says this about operator new: "The pointer returned shall be > suitably aligned so that it can be converted to a pointer of any complete > object type with a fundamental alignment requirement." std::max_align_t has > the strictest fundamental alignment, and, on my system anyway, it's smaller > than 64. > > Is ITK_CACHE_LINE_ALIGNMENT only for performance? Maybe it should be removed? > > Thanks, > > -- > ____________________________________________________________ > Sean McBride, B. Eng [email protected] > Rogue Research www.rogue-research.com > Mac Software Developer Montréal, Québec, Canada > > > _______________________________________________ > Powered by www.kitware.com > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Kitware offers ITK Training Courses, for more information visit: > http://kitware.com/products/protraining.php > > Please keep messages on-topic and check the ITK FAQ at: > http://www.itk.org/Wiki/ITK_FAQ > > Follow this link to subscribe/unsubscribe: > http://www.itk.org/mailman/listinfo/insight-developers _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Kitware offers ITK Training Courses, for more information visit: http://kitware.com/products/protraining.php Please keep messages on-topic and check the ITK FAQ at: http://www.itk.org/Wiki/ITK_FAQ Follow this link to subscribe/unsubscribe: http://www.itk.org/mailman/listinfo/insight-developers
