On Mon, Jul 7, 2008 at 3:22 PM, Greg Smith <gsmith@xxxxxxxxxxxxx> wrote: > On Mon, 7 Jul 2008, Jeffrey Baker wrote: > >> On the single 2.2GHz Athlon, the maximum tps seems to be 1450...what's the >> bottleneck? Is PG lock-bound? > > It can become lock-bound if you don't make the database scale significantly > larger than the number of clients, but that's probably not your problem. > The pgbench client driver program itself is pretty CPU intensive and can > suffer badly from kernel issues. I am unsurprised you can only hit 1450 > with a single CPU. On systems with multiple CPUs where the single CPU > running the pgbench client is much faster than your 2.2GHz Athlon, you'd > probably be able to get a few thousand TPS, but eventually the context > switching of the client itself can become a bottleneck. On a 2GHz Core 2 Duo the best tps achieved is 2300, with -c 8. pgbench itself gets around 10% of the CPU (user + sys for pgbench is 7s of 35s wall clock time, or 70 CPU-seconds, thus 10%). I suppose you could still blame it on ctxsw between pgbench and pg itself, but the results are not better with pgbench on another machine cross-connected with gigabit ethernet. -jwb
