[ale] Memory "free" vs what is truly available

[cfowler]

On Wed, 2007-05-16 at 14:35 -0400, David Tomaschik wrote:
> 
> Buffers and cache will be dropped immediately if the kernel needs the
> RAM.  The 2nd line in the "Free" column is the memory available should
> a
> process need it.  The 1st line is what is truly unused (the kernel
> keeps
> a little for immediate use). 

So take the Free from the second line and determine the percentage of
total.  If it is less than 5% then that would be a problem.  

I've ran into conditions where I was truly using up most memory and swap
usage was low.  The kernel was still killing processes.  I guess in that
case there were many pages that could not be swapped out.