Thanks a lot Simon, that's useful. I will take a look at this process-pinning things.
Arnaud 2013/10/28 Simon Zehnder <szehn...@uni-bonn.de> > First, > > use only the number of cores as a number of thread - i.e. I would not use > hyper threading, etc.. Each core has its own caches and it is always > fortunate if a process has enough memory; hyper threads use all the same > cache on the core they are running on. detectCores() gives me for example 4 > - I know I have 2. I would therefore call makeCluster() with nnode = 2. > mcaffinity() lets you perform a technique called process-pinning (see > process affinity) and is only possible if the OS supports it. It makes > sometimes sense to assign certain processes to certain CPUs such that each > process has enough memory in caches (e.g. for a 16 Core machine using 8 > processes on CPUs 1, 3, 5, 7, 9, 11, 13 and 15; so each process has the > cache of two CPUs). > A lot of functions though are not available for Windows. > > At first it comes always the problem you want to solve and then you look > how much memory will be used in a process and how much you have (more often > the memory bandwidth is the bottleneck and not the computing power). Look > at the architecture of your chips (how much L1 Cache, how much L2 cache). > Then you decide how many cores to use and if it makes sense to pin > processes to certain cores. > > There are no general recipes for parallel computing - each problem is > different. Some problems are even not scalable. > > Simon > > > On 28 Oct 2013, at 17:51, Arnaud Mosnier <a.mosn...@gmail.com> wrote: > > > Thanks Simon, > > > > I already read the parallel vignette but I did not found what I wanted. > > May be you can be more specific on a part of the document that can > provide me hints ! > > > > Arnaud > > > > > > 2013/10/28 Simon Zehnder <szehn...@uni-bonn.de> > > See library(help = "parallel”) > > > > > > On 28 Oct 2013, at 17:19, Arnaud Mosnier <a.mosn...@gmail.com> wrote: > > > > > Hi all, > > > > > > I am quite new in the world of parallelization and I wonder if there > is a > > > way to increase the speed of creation of a parallel socket cluster. The > > > time spend to include threads increase exponentially with the number of > > > thread considered and I use of computer with two 8 cores CPU and thus > > > showing a total of 32 threads in windows 7. > > > Currently, I use the default parameters (type = "PSOCK"), but is there > any > > > fine tuning parameters that I can use to take advantage of this system > ? > > > > > > Thanks in advance for your help ! > > > > > > Arnaud > > > > > > R version 3.0.1 (2013-05-16) > > > Platform: x86_64-w64-mingw32/x64 (64-bit) > > > > > > [[alternative HTML version deleted]] > > > > > > ______________________________________________ > > > 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. > > > > > > [[alternative HTML version deleted]]
______________________________________________ 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.
