Hi there Thanks for your answers. I didn't expect that this would be so complex. Honestly, I don't understand everything you wrote since I'm not an IT specialist. But I read something that reading *.rds files is faster than loading *.Rdata and I wanted to proof that for my system and R version. But thanks anyway for your time.
Cheers Raphael > -----Ursprüngliche Nachricht----- > Von: Jeff Newmiller [mailto:jdnew...@dcn.davis.ca.us] > Gesendet: Dienstag, 22. August 2017 18:33 > An: J C Nash <profjcn...@gmail.com>; r-help@r-project.org; Felber Raphael > Agroscope <raphael.fel...@agroscope.admin.ch> > Betreff: Re: [R] How to benchmark speed of load/readRDS correctly > > Caching happens, both within the operating system and within the C > standard library. Ostensibly the intent for those caches is to help > performance, but you are right that different low-level caching algorithms > can be a poor match for specific application level use cases such as copying > files or parsing text syntax. However, the OS and even the specific file > system drivers (e.g. ext4 on flash disk or FAT32 on magnetic media) can > behave quite differently for the same application level use case, so a generic > discussion at the R language level (this mailing list) can be almost > impossible > to sort out intelligently. > -- > Sent from my phone. Please excuse my brevity. > > On August 22, 2017 7:11:39 AM PDT, J C Nash <profjcn...@gmail.com> > wrote: > >Not convinced Jeff is completely right about this not concerning R, > >since I've found that the application language (R, perl, etc.) makes a > >difference in how files are accessed by/to OS. He is certainly correct > >that OS (and versions) are where the actual reading and writing > >happens, but sometimes the call to those can be inefficient. (Sorry, > >I've not got examples specifically for file reads, but had a case in > >computation where there was an 800% i.e., 80000 fold difference in > >timing with R, which rather took my breath away. That's probably been > >sorted now.) The difficulty in making general statements is that a > >rather full set of comparisons over different commands, datasets, OS > >and version variants is needed before the general picture can emerge. > >Using microbenchmark when you need to find the bottlenecks is how I'd > >proceed, which OP is doing. > > > >About 30 years ago, I did write up some preliminary work, never > >published, on estimating the two halves of a copy, that is, the reading > >from file and storing to "memory" or a different storage location. This > >was via regression with a singular design matrix, but one can get a > >minimal length least squares solution via svd. Possibly relevant today > >to try to get at slow links on a network. > > > >JN > > > >On 2017-08-22 09:07 AM, Jeff Newmiller wrote: > >> You need to study how reading files works in your operating system. > >This question is not about R. > >> ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
