Re: tuning questions

> 
> I've tweaked shared buffers to 8192, pushed sort memory to 2048, vacuum
> memory to 8192, and effective cache size to 10000.
> /proc/sys/kernel/shmmax is set to 1600000000 and /proc/sys/fs/file-max
> is set to 65536. Ulimit -n 3192.

Your sharedmemory is too high, and not even being used effectivey. Your 
other settings are too low.

Ball park guessing here, but I'd say first read (and understand) this:

http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html

Then make shared memory about 10-20% available ram, and set:

((shmmax/1024) - ( 14.2 * max_connections ) - 250 ) / 8.2 = shared_buffers

decrease random_page_cost to 0.3 and wack up sort mem by 16 times, 
effective cache size to about 50% RAM (depending on your other settings) 
and try that for starters.


-- 

Rob Fielding
rob@dsvr.net

www.dsvr.co.uk              Development             Designer Servers Ltd