When swapping starts is because not all programs fit on main memory (RAM) so 
they are going and comming back from seconday memory (disk) all the time, as 
their turn to get executed comes and goes.

Process memory mapping WILL change WHILE you are looking at it, a bit like 
trying to measure the position and speed of the electron.

I guess that the kernel could say 'position 10000h of the virtual memory is 
now mapped into RAM at xxxxx or disk at block yyyyy, but that may change so 
even while you are looking at it. 

For example, when you do the system call to ask the kernel an kernel 
interruption occurs and changes memory mapping of the process you are looking 
at, it goes to RAM, suddenly while you are looking at that info another 
interruption puts it back on disk,
===> you are looking at a process sleeping on disk while you think its on RAM 
cause the monitor program last saw it there.... whats the point? 

 (unless, of course, the monitor gets updated everytime a change is done... 
but updating may produce more changes, another interrupt may occur... and 
back again in the same problem...)

The thing is, if you have 64MB and you are running 128 MB in apps 
simultaneously (all with the same priority) maths say they should be 50% time 
on disk and 50% on RAM.

Correct me if I said something wrong.

Jose

El Lunes 12 Noviembre 2001 13:11, Seak, Teng-Fong escribi�:
>   Jose M. Sanchez wrote:
> >Eh, I was being facetious, hence the smiley.
>
>      Sure I know you're facetious, but I'm afraid newbies would take it
> too seriously and thus acquired wrong knowledge, so I gave more
> explanations.
>
>      Fong

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