>> There is no `free, otherwise unused memory' and the buffer cache
>> guarantees that.

> ... and this is a good thing!  why have memory sitting around useless
> when it could be storing a potentially useful piece of file data?

Without wishing to comment on the claim that this is a good thing, I
offer one possible answer to the (presumably intended as rhetorical)
question: because it is then available significantly faster when the
demand arises.  At the very least you need to load it with what it's
supposed to hold (even if that's just a bzero); if the page is dirty
you'll need to push it out.

					der Mouse

			       mouse@rodents.montreal.qc.ca
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