Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets

On Tue, Sep 18, 2012 at 2:44 AM, Andrea Suisani <sickpig(at)opinioni(dot)net> wrote:
> On 09/14/2012 10:45 AM, Daniel Farina wrote:
>>
>> On Fri, Sep 14, 2012 at 12:40 AM, Nikolay Ulyanitsky <lystor(at)gmail(dot)com>
>> wrote:
>>>
>>> Hi
>>> I compiled the 3.6-rc5 kernel with the same config from 3.5.3 and got
>>> the 15-20% performance drop of PostgreSQL 9.2 on AMD chipsets (880G,
>>> 990X).
>
>
> [cut]
>
>
>>> Kernel config - http://pastebin.com/cFpg5JSJ
>>>
>>> Any ideas?
>>
>>
>> Did you tell LKML? It seems like a kind of change that could be found
>> using git bisect of Linux, albiet laboriously.
>
>
>
> just a pointer to LKML thread:
>
> https://lkml.org/lkml/2012/9/14/99

There's some interesting discussion of postgres spinlocks in the thread:

"Yes, postgress performs loads better with it's spinlocks, but due to
that, it necessarily _hates_ preemption."

merlin