Re: Move PinBuffer and UnpinBuffer to atomics

Hi,

On 11/09/2015 05:10 PM, Andres Freund wrote:
>> Each graph has a full initdb + pgbench -i cycle now.
>
> That looks about as we'd expect: the lock-free pinning doesn't matter
> and ssynchronous commit is beneficial. I think our bottlenecks in write
> workloads are sufficiently elsewhere that it's unlikely that buffer pins
> make a lot of difference.
>

Using

  https://commitfest.postgresql.org/7/373/

shows that the CLog queue is max'ed out on the number of client connections.

> You could try a readonly pgbench workload (i.e. -S), to see whether a
> difference is visible there. For a pgbench -S workload it's more likely
> that you only see significant contention on larger machines. If you've a
> workload that touches more cached buffers, it'd be visible earlier.
>

Yeah, basically no difference between the 4 -S runs on this setup.

>> I know, I have a brown paper bag somewhere.
>
> Why? This looks as expected, and the issues from the previous run were
> easy to make mistakes?
>

I should have known to do the full cycle of initdb / pgbench -i in the
first place.

Best regards,
  Jesper