Bob Dusek <redusek@gmail.com> wrote:
> Scott Marlowe <scott.marlowe@gmail.com>wrote:
>> Bob Dusek <redusek@gmail.com> wrote:
>>> 4X E7420 Xeon, Four cores (for a total of 16 cores)
>> What method of striped RAID?
>
> RAID-0
I hope you have a plan for what to do when any one drive in this
array fails, and the entire array is unusable.
Anyway, my benchmarks tend to show that best throughput occurs at
about (CPU_count * 2) plus effective_spindle_count. Since you seem
to be fully cached, effective_spindle_count would be zero, so I
would expect performance to start to degrade when you have more than
about 32 sessions active.
> We actually see degredation when we get more than 40 concurrent
> requests.
Close enough.
> when we run 200+ requests, we see multi-second queries.
No surprise there. Your vmstat output suggests that context
switches are becoming a problem, and I wouldn't be surprised if I
heard that the network is an issue. You might want to have someone
take a look at the network side to check.
You want to use some connection pooling which queues requests when
more than some configurable number of connections is already active
with a request. You probably want to run that on the server side.
As for the postgresql.conf, could you show what you have right now,
excluding all comments?
-Kevin
