Re: Sudden Query slowdown on our Postgresql Server

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Sebastian Melchior <webmaster(at)mailz(dot)de>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Sudden Query slowdown on our Postgresql Server
Date: 2012-03-23 05:19:03
Message-ID: CAOR=d=0X0Z1M_X4VMOKnvbr1WS2V02yAqSasrDWng9cr8hhVhw@mail.gmail.com
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What does vmstat say about things like context switches / interrupts per second?

On Thu, Mar 22, 2012 at 10:53 PM, Sebastian Melchior <webmaster(at)mailz(dot)de> wrote:
> Hi,
>
> we already used iostat and iotop during times of the slowdown, there is no sudden drop in I/O workload in the times of the slowdown. Also the iowait does not spike and stays as before.
> So i do not think that this is I/O related. As the disks are SSDs there also still is some "head room" left.
>
> Sebastian
>
> On 23.03.2012, at 05:48, Scott Marlowe wrote:
>
>> I'd suggest the handy troubleshooting tools sar, iostat, vmstat and iotop
>>
>> On Thu, Mar 22, 2012 at 10:37 PM, Sebastian Melchior <webmaster(at)mailz(dot)de> wrote:
>>> Hi,
>>>
>>> yeah we log those, those times do not match the times of the slowdown at all. Seems to be unrelated.
>>>
>>> Sebastian
>>>
>>>
>>> On 23.03.2012, at 01:47, Stephen Frost wrote:
>>>
>>>> * Sebastian Melchior (webmaster(at)mailz(dot)de) wrote:
>>>>> Does anyone have any idea what could cause this issue or how we can further debug it?
>>>>
>>>> Are you logging checkpoints?  If not, you should, if so, then see if
>>>> they correllate to the time of the slowdown..?
>>>>
>>>>       Thanks,
>>>>
>>>>               Stephen
>>>
>>>
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>>
>>
>> --
>> To understand recursion, one must first understand recursion.
>

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