clearing the buffer cache

Hi,

I was doing some performance checks and wondered what the best way to
clear out the shared buffers is?  With the recent improvements in buffer
management it appears a simple SELECT * FROM large_table; doesn't help
here!

I was hoping for a function I could call, or maybe some variable I write
to, that would cause the contents to be invalidated.

--
  Sam  http://samason.me.uk/