On 27/01/2011 11:31, Michael Kohl wrote:
> Hi all,
>
> we are running a fairly big Ruby on Rails application on Postgres 8.4.
> Our traffic grew quite a bit lately, and since then we are facing DB
> performance issues. System load occasionally explodes (around 170
> yesterday on a 16 core system), which seems to be caused by disk I/O
> (iowait in our Munin graphs goes up significantly during these
> periods). At other times the laod stays rather low under pretty much
> the same circumstances.
Is there any way you can moderate the number of total active connections
to the database to approximately match the number of (logical) CPU cores
on your system? I.e. some kind of connection pool or connection
limiting? This should help you in more ways than one (limit PG lock
contention, limit parallel disk IO).