Doran, Harold wrote: > Dear List: > > I am very much a unix neophyte, but recently had a Ubuntu box installed > in my office. I commonly use Windows XP with 3 GB RAM on my machine and > the Ubuntu machine is exactly the same as my windows box (e.g., > processor and RAM) as far as I can tell. > > Now, I recently had to run a very large lmer analysis using my windows > machine, but was unable to due to memory limitations, even after > increasing all the memory limits in R (which I think is a 2gig max > according to the FAQ for windows). So, to make this computationally > feasible, I had to sample from my very big data set and then run the > analysis. Even still, it would take something on the order of 45 mins to > 1 hr to get parameter estimates. (BTW, SAS Proc nlmixed was even worse > and kept giving execution errors until the data set was very small and > then it ran for a long time) > > However, I just ran the same analysis on the Ubuntu machine with the > full, complete data set, which is very big and lmer gave me back > parameter estimates in less than 5 minutes. > > Because I have so little experience with Ubuntu, I am quite pleased and > would like to understand this a bit better. Does this occur because R is > a bit friendlier with unix somehow? Or, is this occuring because unix > somehow has more efficient methods for memory allocation? > Probably partly the latter and not the former (we try to make the most of what the OS offers in either case), but a more important difference is that we can run in 64 bit address space on non-Windows platforms (assuming that you run a 64 bit Ubuntu).
Even with 64 bit Windows we do not have the 64 bit toolchain in place to build R except as a 32 bit program. Creating such a toolchain is beyond our reach, and although progress is being made, it is painfully slow (http://sourceforge.net/projects/mingw-w64/). Every now and then, the prospect of using commercial tools comes up, but they are not "plug-compatible" and using them would leave end users without the possibility of building packages with C code, unless they go out and buy the same toolchain. > I wish I knew enough to even ask the right questions. So, I welcome any > enlightenment members may add. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.