BTW, I've just checked a hunch. I did not believe R_IsNaNorNA is actually used in base R on a system with IEEE arithmetic (and I removed it to test that). That suggests you have not actually tested inlining it and your analysis is seriously flawed.
(Note to Deepayan: it is not a documented entry point, so please use ISNAN as documented.) On Fri, 14 May 2004, Prof Brian Ripley wrote: > On Fri, 14 May 2004, Li Long wrote: > > > Hi, R core developers, And BTW, R-devel is not the address of the core developers. > > I work in the Swiss Institute of Bioinformatics. We have two clusters of > > Intel Itanium2 clusters for bioinformaticians to crank their data. One > > piece of software they use heavily is R and BioConductors. I ported the R > > codes and R packages to this platform already, and am working on > > optimizing their performance. I'm using Intel C/C++ compiler on this > > platform running Linux. One of my findings is that turning some functions > > in R to "inline" functions boost performance significantly. > > > > While R follows strict C89 standard right now, there're quite some good > > reasons to relax the rule somewhat. From my experience in software > > development in industry, I understand very well both the portability issue > > and backward compatability issue, I also see the hidden cost of holding > > back for too long and not fully achieving the potential of new technology, > > Could you then please quantify that hidden cost? > > > I recommend that we allow "inline" functions in R's C codes. > > In what sense do `we' not allow it? And who is `we'? > > The problem is that very few compilers fully support C99, and others have > different ways to indicate inlining. So a configure test is needed. I am > sure that if you provide one together with patches to parts of the code > where you find inlining beneficial, the real `we' would consider it > carefully. Especially if the `hidden cost' is noticeable. > > .... > > > In R, there are quite some simple functions that are called extremely > > often, such as "R_IsNaNorNA", "R_finite", etc. They are used in heavy > > loops quite a lot. They disrupt the pipelining, and negatively affect the > > performance of the software. For instance, on IA64, system call of > > "isnan" cost 4 cycles, while a wrapper like "R_IsNaNorNA" could cost > > several times more. > > However, one of the motivations of eliminating support for non-IEEE-754 > platforms in R 2.0.0 is to enable some of this baggage to be eliminated. > But the wrapper is there for a good reason: to get the right answer. > > Since I gather you have suitably modified code, it would be helpful to > your case to provide data > > - on real problems > - on a mainstream platform. > > of the actual performance impact of not inlining. > > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
