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

On 08/11/12 02:33, David Boreham wrote:
> 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.
>
>
>
>

Interesting - I was wondering if a single socket board would behave 
differently (immediately after posting of course)...I've got an i3 home 
system that scales nicely even with hyperthreading on (2 cores, 4 
typerthreads).

Cheers

Mark