On Mon, Jan 11, 2010 at 12:17 PM, Kevin Grittner < kevin.gritt...@wicourts.gov> wrote:
> Bob Dusek <redu...@gmail.com> wrote: > > Scott Marlowe <scott.marl...@gmail.com>wrote: > >> Bob Dusek <redu...@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. > Point noted. > 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. > That's a little disheartening for a single or dual CPU system. > > 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. > This is all happening on a LAN, and network throughput doesn't seem to be an issue. It may be a busy network, but I'm not sure about a problem. Can you elaborate on your suspicion, based on the vmstat? I haven't used vmstat much. > > 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? > The problem with connection pooling is that we actually have to achieve more than 40 per second, which happens to be the sweet spot with our current config. I posted our changes from the default in a reply to another message. I don't want to duplicate. Can you check those out? > > -Kevin >
