Re: pgbench vs. wait events

Hi,

I decided to do some testing on hydra (IBM-provided community
resource, POWER, 16 cores/64 threads, kernel 3.2.6-3.fc16.ppc64) using
the newly-enhanced wait event stuff to try to get an idea of what
we're waiting for during pgbench.  I did 30-minute pgbench runs with
various configurations, but all had max_connections = 200,
shared_buffers = 8GB, maintenance_work_mem = 4GB, synchronous_commit =
off, checkpoint_timeout = 15min, checkpoint_completion_target = 0.9,
log_line_prefix = '%t [%p] ', max_wal_size = 40GB, log_checkpoints =
on.  During each run, I ran this psql script in another window and
captured the output:

\t
select wait_event_type, wait_event from pg_stat_activity where pid !=
pg_backend_pid()
\watch 0.5

Then, I used a little shell-scripting to count up the number of times
each wait event occurred in the output.  First, I tried scale factor
3000 with 32 clients and got these results: