>> Read cache of course does not need to be flushed and can simply be
>> dumped when the memory is needed, and so Linux will keep more or
>> less unlimited amounts of read cache until it needs the memory for
>> something else ....
>
> Right, that's the normal behavior. Except not on this machine.
So this turned out to be a Linux kernel issue. Will document it on
www.databasesoup.com.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com