Re: CPUs for new databases

On Wed, Oct 27, 2010 at 12:03 PM, Josh Berkus <josh@agliodbs.com> wrote:
> On 10/26/10 6:14 PM, Scott Marlowe wrote:
>>   There was an earlier thread with
>> Greg and I in it where we posted the memory bandwidth numbers for that
>> machine and it was insane how much data all 48 cores could pump into /
>> out of memory at the same time.
>
> Well, the next step then is to do some database server benchmarking.
>
> My experience has been that PostgreSQL scales poorly past 30 cores, or
> even at lower levels depending on the workload.  So it would be
> interesting to see if the memory bandwidth on the AMDs makes up for our
> scaling issues.

Which OSes have you tested it on?  And what hardware?  For smaller
operations, like pgbench, where a large amount of what you're working
on fits in cache, I get near linear scaling right up to 48 cores.
Overall performance increases til about 50 threads, then drops off to
about 60 to 70% peak for the next hundred or so threads I add on.