The last component seems the most meaningful since its the amount of time you actually waited for the code to run.
On Sat, Feb 27, 2010 at 11:44 PM, Ravi Varadhan <rvarad...@jhmi.edu> wrote: > > Thanks, Gabor. Your reply is helpful, but it still doesn't answer whether I > should use the sum of the first two components of system.time (user + system > CPU) or only the first one (user CPU). > > Ravi. > ____________________________________________________________________ > > Ravi Varadhan, Ph.D. > Assistant Professor, > Division of Geriatric Medicine and Gerontology > School of Medicine > Johns Hopkins University > > Ph. (410) 502-2619 > email: rvarad...@jhmi.edu > > > ----- Original Message ----- > From: Gabor Grothendieck <ggrothendi...@gmail.com> > Date: Saturday, February 27, 2010 9:47 pm > Subject: Re: [R] Which system.time() component to use? > To: Ravi Varadhan <rvarad...@jhmi.edu> > Cc: r-help@r-project.org > > >> Try this: >> >> > system.time(Sys.sleep(60)) >> user system elapsed >> 0.00 0.00 60.05 >> > pt <- proc.time(); Sys.sleep(60); proc.time() - pt >> user system elapsed >> 0.00 0.00 60.01 >> >> On Sat, Feb 27, 2010 at 9:33 PM, Ravi Varadhan <rvarad...@jhmi.edu> wrote: >> > >> > Hi, >> > >> > The `system.time(expr)' command provide 3 different times for >> evaluating the expression `expr'; the first two are user and system >> CPUs and the third one is total elapsed time. Suppose I want to >> compare two different computational procedures for performing the same >> task, which component of `system.time' is most meaningful in the sense >> that it most accurately reflects the computational effort of the >> algorithm, and does not depend upon the idiosyncrasies of the >> operating system. >> > >> > I have always been using the first component of `system.time', which >> is the user CPU. Should I use the sum of user and system CPU or is >> the total elapsed time a better measure? I would appreciate UseR's >> feedback on this. >> > >> > Thanks very much. >> > >> > Best, >> > Ravi. >> > ____________________________________________________________________ >> > >> > Ravi Varadhan, Ph.D. >> > Assistant Professor, >> > Division of Geriatric Medicine and Gerontology >> > School of Medicine >> > Johns Hopkins University >> > >> > Ph. (410) 502-2619 >> > email: rvarad...@jhmi.edu >> > >> > ______________________________________________ >> > R-help@r-project.org mailing list >> > >> > PLEASE do read the posting guide >> > and provide commented, minimal, self-contained, reproducible code. >> > > ______________________________________________ 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.