[SGVLUG] used memory on a 4 GB system.

[Emerson, Tom]

> -----Original Message----- Of James Neff
> 
> I ran top and here are the results:
> 
> Mem:  4039408k total,4004660k used,  34748k free,   59444k buffers
> Swap: 2031608k total,    128k used,2031480k free, 3713780k cached
[...]
> This is a dual Opteron system (2 processors) with 2 GB of RAM 
> for each processor.
> 
> My question is, why does it say almost all of the memory is used?  Is 
> this something I should be worried about or am I doing something
wrong?

It is my understanding that the system will use as much memory as
possible for caching and "buffers", though I see two things seemingly
"odd" about what top is reporting:

  59 meg used for "buffers" [would have expected that to be most of the
4 gig]
  3 and 3/4 gig of your 2 gig swap file is "cached..."

Or maybe I'm just reading that wrong, since it says you are only using a
minimum of your "swap" file (meaning you probably aren't hitting it at
all...) -- yeah, this makes more sense:

   of "real" memory, you're "using":
     ::    59 meg in "buffers"
     :: 3,713 meg of your disk has been "cached"
     ::    34 meg is "free"
       ------
        3,806 meg is NOT used by applications

    4,039 - 3,806 leaves 233 meg used "by applications" (and the OS
proper)

It's the caching that is using up the majority of your memory...

I suspect that if you were to "cat" a 30+ megabyte file to /dev/null and
check memory again, that "free" space would decrease to nearly zero (and
the "cache" would increase by a corresponding amount)