Thanks.

I also did some parallel computing. Here are some time I spent by using
'snowfall' package on intel centrino 2 laptop (2 cores) on windows 7.

   user  system elapsed
   0.24    0.05 2442.77

Libo

On Wed, Feb 22, 2012 at 12:53 AM, Martin Maechler <
maechler@stat.math.ethz.ch> wrote:

> >>>>> "LS" == Libo Sun <libosun@rams.colostate.edu>
> >>>>>     on Tue, 21 Feb 2012 21:09:54 -0700 writes:
>
>    > Thanks. Shall I sum the user time and system time, which
>    > roughly equals to the elapsed time?
>
> No.  Rather just use the  user time,
> i.e.  proc.time()[[1]]
>    system.time()[[1]]   etc
>
> That's typically good enough [as long as you don't use
> internally multithreaded BLAS, or  parallelize / distribute your job,
> or other things you won't be doing (yet)].
>
> Martin Maechler, ETH Zurich
>
>   > I also tried to improve the code by using 'cmpfun(myfunction)' in
>   > 'compiler' package, however, it doesn't help too much.
>
>   > Libo
>
> > On Tue, Feb 21, 2012 at 8:11 PM, R. Michael Weylandt <
> > michael.weylandt@gmail.com> wrote:
>
> > The time relationships aren't strictly linear between any of the three
> > measures, but *very generally* I've interpreted them as something
> > like:
> >
> > User: stuff you do (i.e., doing all the commands)
> > System: stuff at the OS level (memory allocations and whatnot)
> > Elapsed: Clock time
> >
> > None is a great measure in isolation, but the system time is not the
> > worrisome one here: it looks like your script takes about a day and a
> > half to run....that might be ok (and perhaps unavoidable) but it looks
> > like there might be value in trying to squeeze some speed out of your
> > script. A simple thing like byte-compiling that gives 2x speedup would
> > be huge here.
> >
> > Michael
> >
> > On Tue, Feb 21, 2012 at 10:06 PM, Libo Sun <libosun@rams.colostate.edu>
> > wrote:
> > > Hi all,
> > >
> > > I got this time for my code,
> > >
> > >> proc.time()-pt
> > >      user     system    elapsed
> > > 132541.743      0.004 132533.526
> > >
> > > As you can see, there is huge difference btw elapsed time and system
> > time.
> > > Does that mean lots of I/O? Or some bad coding?
> > >
> > > Thanks,
> > > Libo
>

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