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

[Simon Urbanek]

Matthew,

contrary to the subject this has nothing to do with R, you are just  
making incorrect assumptions about memory types in OS X. Please  
consider reading the appropriate documentation:
http://developer.apple.com/documentation/Performance/Conceptual/ManagingMemory/Articles/AboutMemory.html
Inactive pages still need to be paged out when more resident RAM is  
requested. Also it is not R who is swapping anyway ...

Cheers,
Simon


On Feb 22, 2008, at 12:08 PM, Matthew Keller wrote:

> 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!
>
> Matt
>
>
>
>
>
>
>> sessionInfo()
> R version 2.6.2 alpha (2008-01-29 r44238)
> i386-apple-darwin9.1.0
>
> locale:
> C
>
> 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()
> $platform
> [1] "i386-apple-darwin9.1.0"
>
> $arch
> [1] "i386"
>
> $os
> [1] "darwin9.1.0"
>
> $system
> [1] "i386, darwin9.1.0"
>
> $status
> [1] "alpha"
>
> $major
> [1] "2"
>
> $minor
> [1] "6.2"
>
> $year
> [1] "2008"
>
> $month
> [1] "01"
>
> $day
> [1] "29"
>
> $`svn rev`
> [1] "44238"
>
> $language
> [1] "R"
>
> $version.string
> [1] "R version 2.6.2 alpha (2008-01-29 r44238)"
>
> -- 
> Matthew C Keller
> Asst. Professor of Psychology
> University of Colorado at Boulder
> www.matthewckeller.com
>
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