Question about Virtual Memory

[James Fillman]

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I'm trying to understand how the 2.4 kernel behaves with respect to 
caching. I'm running the 2.4.17 kernel on an i686. The server is running 
heartbeat, apache, tomcat, and a java based message routing application. 99% 
of the work is comming from the java application which produces a lot of disk 
and network I/O. 
Am I correct in saying that the kernel will cache disk writes to memory if 
there is ample free RAM? Then syncing it to disk at a later time?

With the above mentioned applications NOT running, %swapused = 0, disk cache 
= 0. I've observed that when the applications start up, the kernel slowly 
starts allocating free RAM for caching. It will stabalize with ~6MB of RAM 
free. That's fine. But what I don't understand is that at the same time, swap 
usage starts to increase and after a day or so, stabalizes at ~15MB. What is 
being  swapped out? Is the VMM utilizing swap when it's caching?

cheers,
James Fillman
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