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

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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


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