Re: HT on or off for E5-26xx ?

On 11/6/2012 9:16 PM, Mark Kirkwood wrote:
>
>
> I've been benchmarking a E5-4640 (4 socket) and hyperthreading off 
> gave much better scaling behaviour in pgbench (gentle rise and flatten 
> off), whereas with hyperthreading on there was a dramatic falloff 
> after approx number clients = number of (hyperthreaded) cpus. The box 
> is intended to be a pure db server, so we are running with 
> hyperthreading off.

It looks like this syndrome is not observed on my box, likely due to the 
much lower number of cores system-wide (12).
I see pgbench tps increase nicely until #threads/clients == #cores, then 
plateau. I tested up to 96 threads btw.

We're waiting on more memory modules to arrive. I'll post some test 
results once we have all 4 memory banks populated.