der Mouse is right except for certain ocasions/enviroments where you
don't know when you'll need free memory pages. For example I can
point network appliances/dedicated devices. Assuming routing/
firewalling/accounting is the high-level priority job for this device you
should not let low-priority job (as logging) to interfere the productivity
of high-priority ones. Say, you have this logging software using all the
pages in the VM system and in a certain moment you have to process
some traffic in a "no free memory" enviroment. Starting VM/cache
syncroniztaion may degrade network performance, firewall processing,
etc.
So, my point is "It is a good idea to keep pages in memory when someone
will use them, except for the situations like the one described above"

     Ivo Vachkov
     Network Administrator
     Unilans Networking

der Mouse wrote:

 >>> If you will *never* read it, I have to ask, why bother writing it?
 >>
 >>
 >> Obviously its for logging as the poster said.
 >
 >
 >
 > Yes, but why bother writing logs that will never be read?
 >
 > (Actually, I got an off-list explanation: it _will_ be read, just not
 > until much later, and then only to copy it off-machine.)
 >
 > My next question: are you sure you need to?  It's been a while since I
 > worked with -current, but when I last did (mid-2002), it behaved as
 > described - but the "duplicate" memory was reclaimed instantly as soon
 > as anyone else wanted memory and there was none free.  After all, why
 > not cache it until someone wants the pages?  Doesn't hurt anything, as
 > long as you keep enough records to know the page can be thrown away
 > instantly as soon as anyone wants it.
 >
 > /~\ The ASCII                der Mouse
 > \ / Ribbon Campaign
 >  X  Against HTML           mouse@rodents.montreal.qc.ca
 > / \ Email!         7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B
 >
 >