To be more precise I used constant number of threads (128 and 1024) to compare with previous results. The quadratic dependency exists everywhere, see new graph.
> Q: Did you check that pgbench or the OS does not have
> O(n_active_connections) or O(n_active_threads) overhead per worker
> during thread creation or connection establishment, e.g. by varying
> the number of threads used to manage these N clients? I wouldn't be
> surprised if there are inefficiencies in e.g. the threading- or
> synchronization model that cause O(N) per-thread overhead, or O(N^2)
> overall when you have one thread per connection.
