Instead of getting an estimate of the number of kernel buffers,
allocating memory for them, requesting all the metadata contents of
these buffers (and repeating in the unlikely case of the number of
buffers increasing too much since the estimate) and then straight away
throwing all the contents out just to count how many buffers there were,
just get the initial estimate from the kernel and subtract the slop.

Reduces system CPU usage of "systat vm" by approx 80% for any system
with a reasonable number of buffers.

(simonb)