🚀 go-pugleaf

First things first, a description of my setup.

        80386-40, no copro
        4mb RAM, IDE HD's (single controller), ext2 fs
        ET4000 video card
        vanilla ALPHA-pl14{p,x,z} pl15

Lately I've noticed that the amount of system memory used for the
buffer cache (as reported by 'free' or 'cat /proc/meminfo') is
behaving (at least what I see as) weirdly.  The cache size will
start out at zero, as would be expected, and slowly grow, as is
expected, but once past a certain size, will not shrink again
below that size.  This size is (usually) 1500k, but varies
depending on how many filesystems I have mounted (for example if
I unmount some filesystems, then the size will shrink).

Firstly, is this normal? If so, can somebody explain the reasons
behind this behaviour.

Secondly, if this *is* normal, doesn't such behaviour violate the
reasons for a shared memory between processes/buffer cache?  The
cache will seemingly never shrink below the given size, no matter
what the system is doing (even when it is thrashing like you
wouldn't believe), and I really don't like the idea of permanently
giving up half of my avalailble memory to the buffer cache.

 - Mike