Re: postgres 9.3 vs. 9.4

On 19/09/14 19:24, Mkrtchyan, Tigran wrote:
>
>
> ----- Original Message -----
>> From: "Mark Kirkwood" <mark.kirkwood@catalyst.net.nz>
>> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
>> Cc: "Merlin Moncure" <mmoncure@gmail.com>, "postgres performance list" <pgsql-performance@postgresql.org>
>> Sent: Friday, September 19, 2014 8:26:27 AM
>> Subject: Re: [PERFORM] postgres 9.3 vs. 9.4
>>
>> On 19/09/14 17:53, Mkrtchyan, Tigran wrote:
>>>
>>>
>>> ----- Original Message -----
>>>> From: "Mark Kirkwood" <mark.kirkwood@catalyst.net.nz>
>>
>>>> Further to the confusion, here's my 9.3 vs 9.4 on two M550 (one for 9.3
>>>> one for 9.4), see below for results.
>>>>
>>>> I'm running xfs on them with trim/discard enabled:
>>>>
>>>> $ mount|grep pg
>>>> /dev/sdd4 on /mnt/pg94 type xfs (rw,discard)
>>>> /dev/sdc4 on /mnt/pg93 type xfs (rw,discard)
>>>>
>>>>
>>>> I'm *not* seeing any significant difference between 9.3 and 9.4, and the
>>>> numbers are both about 2x your best number, which is food for thought
>>>> (those P320's should toast my M550 for write performance...).
>>>
>>> cool! any details on OS and other options? I still get the same numbers
>>> as before.
>>>
>>
>> Sorry, Ubuntu 14.04 on a single socket i7 3.4 Ghz, 16G (i.e my workstation).
>>
>> I saw the suggestion that Didier made to run 9.3 on the SSD that you
>> were using for 9.4, and see if it suddenly goes slow - then we'd know
>> it's something about the disk (or filesystem/mount options). Can you
>> test this?
>
>
> swapping the disks did not change the results.
> Nevertheless, I run the same test on my fedora20 laptop
> 8GB RAM, i7 2.2GHz and got 2600tps! I am totally
> confused now! Is it kernel version? libc?
>
>

Well, that's progress anyway!

I guess you could try fedora 20 on the Dell server and see if that makes
any difference. But yes, confusing. Having been dealing with a high end
Dell server myself recently (R920), some re-reading of any manuals you
can find might be useful, we were continually surprised how easy it was
to have everything configured *slow*... and the detail in the
manuals...could be better!

Cheers

Mark