I have a 16GB RAM Machine with windows 64 bit.If I run a model in R it uses only 2GB and remaining memory is free. I have run the same model in a 4GB machine which takes 4 hours to give the result,So I upgraded to 16GB RAM ,but still then R takes the same 4 hours to run the same model in 16GB machine also.R is not using more than 2GB of RAM.
Any idea why R is not using the entire RAM avaiable.