> Darren New <dne### [at] sanrrcom> wrote:
>> But the question of "how do you know the memory is 'consumed'?" would 
>> likely provide clues towards answering the question of who is using it.
> 
>   That's indeed quite relevant.
> 
>   The amount of available "free memory" is quite an irrelevant number in
> any modern OS (and most of the older ones too). Even Windows. That number
> doesn't really say anything. IMO it could and should be removed from the
> basic user interface because it only causes confusion and serves no useful
> purpose. Even some very experienced users get confused by that number.
> Usually many people get worried if the amount of free memory is very low,
> even though there's often absolutely nothing to it.
> 
>   Sure, the number is telling the amount of memory currently not used by
> anything. However, knowing the amount of memory not used currently by
> anything is basically useless information because it tells you nothing
> about the state of the system. It does *not* tell how much memory will
> be available for a program you will be next starting. It does *not* tell
> you that the system is running out of memory and that something is wrong
> because of that.
> 
>   Most OSes will use available free memory for internal things. This is
> usually pretty "light" form of usage of memory in that immediately when
> a new process requests more memory than is currently unused, that memory
> used by the OS for its own things will be immediately freed for the process
> to use.
>   It may very well happen that the OS reports that there's only 1MB of free
> memory in a 1GB system, yet when you start a program requiring half of a
> gigabyte of memory, it runs smoothly without even the slightest bit of
> swapping or anything. The OS simply stopped using part of that memory and
> freed it for the process to use.
> 
>   That's why the "memory free" number doesn't really say anything.
> 

Free RAM is *wasted RAM*. That's why Vista has such an "aggressive" disk 
cache, pre-fetching files even before you open them.

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