Re: PostgreSQL performance on FreeBSD

27 jun 2014 kl. 18:34 skrev Konstantin Belousov <kostikbel_at_gmail.com>:

> On Fri, Jun 27, 2014 at 10:57:53AM -0400, John Baldwin wrote:
>> On Friday, June 27, 2014 8:56:13 am Konstantin Belousov wrote:
>>> Hi,
>>> I did some measurements and hacks to see about the performance and
>>> scalability of PostgreSQL 9.3 on FreeBSD, sponsored by The FreeBSD
>>> Foundation.
>>> 
>>> The results are described in https://kib.kiev.ua/kib/pgsql_perf.pdf.
>>> The uncommitted patches, referenced in the article, are available as
>>> https://kib.kiev.ua/kib/pig1.patch.txt
>>> https://kib.kiev.ua/kib/patch-2
>> 
>> Did you run the same benchmark on the same hardware with any other OS's to 
>> compare results?
> 
> No.
> 
> FWIW, before the failing after the 30 clients is corrected, I do not
> think it is much interesting to do such comparision.

This is great work!

Does anybody know how far back in FreeBSD versions using posix semaphore instead of sysv would make a difference?  It seems we need a rather current version? 8.x did not support it at all, at some point at lest, and in 9 it was buggy. I could add he patch-2 to the port, but I reckon it needs a conditional based on FreeBSD version?

The clang bug should go upstreams, right?

I have seen similar curves, presented by Greg Smith (PostgreSQL hacker) where he concluded that there is no point in running more than 50 concurrent connections. This was for Linux. In your measures, the knee is at 30. That's said, FreeBSD could and should do better, but probably there is a limit where there will be a knee in the graph and performance will drop. It should be more than 30, though, as you rightly commented.

Do you any ideas to pursue this further apart from complicated rewrites like DragonFly?

Palle