[R-SIG-Mac] R not accessing inactive RAM in Leopard

Matthew Keller mckellercran at gmail.com
Fri Feb 22 18:08:00 CET 2008

Hello all,

I am not certain whether this issue pertains to the Leopard OS or to R
or some combination. I have been running 64 bit R for the first time
over the last couple of weeks and so am still learning the ins and
outs of it. I have 18GB RAM on a 3.0 2008 Mac Pro. My R version is
posted below.

>From the "top" command in terminal, I'm showing 5GB of inactive RAM.
>From the Leopard Activity Monitor page,  with regard to inactive
memory, it says "This information [inactive RAM] is no longer being
used and has been cached to disk, but it will remain in RAM until
another application needs the space. Leaving this information in RAM
is to your advantage if you (or a client of your computer) come back
to it later."

However, yesterday R accessed 12GB RAM and then started swapping to
hard drive (the pageouts went from 0 to 327000), all the while that
5GB inactive RAM just sat right where it was.  I had been expecting R
to access this inactive RAM once it ran out of free RAM rather than
swapping to hard drive. I can't believe that the Leopard OS is this
inefficient with memory allocation, so I'm guessing I'm not
understanding something. Does anyone understand why this might be
happening, and/or have any ideas about how to get R to access that
inactive memory?

Thank you!


> sessionInfo()
R version 2.6.2 alpha (2008-01-29 r44238)


attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_2.6.2
> R.Version()
[1] "i386-apple-darwin9.1.0"

[1] "i386"

[1] "darwin9.1.0"

[1] "i386, darwin9.1.0"

[1] "alpha"

[1] "2"

[1] "6.2"

[1] "2008"

[1] "01"

[1] "29"

$`svn rev`
[1] "44238"

[1] "R"

[1] "R version 2.6.2 alpha (2008-01-29 r44238)"

Matthew C Keller
Asst. Professor of Psychology
University of Colorado at Boulder

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