"adjusting" / control Swapping

["Niels Dettenbach" <nd%syndicat.com@localhost>]

Dear all,

how can i control the swapping behaviour within a NetBSD system?

I have some NetBSD Xen guests with around 3 GB of RAM. I've added 3 swap 
partitions (on different medias) with priority 1, 2 and 3 witha volume of 5 GB 
swap. The swap is needed as there are peaks of required memory sometimes (once 
or twice a month) where the system stops with out of mem otherwise. In most 
time the swap is not required, but used (I assume i.e. for file caching). If i 
restart several of that mem-pigs / deamons (i.e. once a day) within the system 
the swap was wiped out and the sytsm seems to run faster (with less load). 
There are daemons who doenst offer control of their caching or mem-usage 
behaviour byself.

The swap is relatively fast but the system slows down when there several Gigs 
of swap are used. 

Limiting memory usage of the largest processes seems not suitable as they need 
more from time to time.

On Linux there are switches like swappiness which allow to control the usage of 
the swaps. How can i control the swapping under NetBSD?

Many thanks for your time,
best regards,

Niels.
---
Niels Dettenbach
http://www.syndicat.com