> 28 jun 2014 kl. 12:21 skrev Konstantin Belousov <kostik...@gmail.com>:
>> On Sat, Jun 28, 2014 at 12:08:39PM +0200, Palle Girgensohn wrote:
>>> 27 jun 2014 kl. 18:34 skrev Konstantin Belousov <kostik...@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:
>>>>> I did some measurements and hacks to see about the performance and
>>>>> scalability of PostgreSQL 9.3 on FreeBSD, sponsored by The FreeBSD
>>>>> The results are described in https://kib.kiev.ua/kib/pgsql_perf.pdf.
>>>>> The uncommitted patches, referenced in the article, are available as
>>>> Did you run the same benchmark on the same hardware with any other OS's to
>>>> compare results?
>>> 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?
> I recommend to add it as an option. The currently supported versions
> of stable/9 and higher have new posix semaphores implementation.
> The stable/8 also has posix semaphores, but there it is kernel-based
> interface, I do not plan to evaluate it in any way.
According to one source, posix semaphores uses O(N^2) file descriptors, where N
is the number of connections. Do you know if this is true? (I'll try it,
naturally, just checking).
>> The clang bug should go upstreams, right?
> I believe there is already some activity about it. I do not follow
> clang development.
Sounds good enough.
>> 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?
> I do.
> The scope of the current work was done to obtain understanding where do we
> and, if possible, evaluate ideas, possibly in the hackish way. I hope
> and almost sure that this will be continued, but cannot provide any time
Great. If you need help testing, I might be able to help.
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