When does swap decreases

[Francisco Reyes]

On Mon, 20 Jun 2005, Dan Nelson wrote:

> In the last episode (Jun 20), Francisco Reyes said:
>> How wonder how the current method affects performance. Basically if
>> there is a surge of memory usage and processes start that use the
>> swap and these processes are long lived.. I wonder if performance
>> will be affected.
>
> There may even be a performance gain, since if the system comes under
> memory pressure again, some of the in-memory pages of those long-lived
> processes previously copied to swap may still be clean, and the system
> won't even have to page them out; it can simply free the RAM.  I can't
> think of any way for there to be a performance hit, unless you actually
> run out of swap.


I must really be missing something here..
My case. 384MB of RAM
For several days swap was 0.
That to me means that everything was fitting nicely into memory.

At one point in the last few days I must have opened too many 
windows/apps.. and the OS actually had to use swap.

Once I closed programs (xpecially X, Opera, and other GUI apps) I expected 
the swap would go back to 0.

Swap remained at 10MB.. Whatever processes are using the swap aren't they 
accessing the HD?

Can there be swap usage, yet the OS doing all the work on memory?