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.
