Re: postgresql latency & bgwriter not doing its job

On Wed, Aug 27, 2014 at 3:32 AM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:

>
> Hello Andres,
>
> [...]
>>
>> I think you're misunderstanding how spread checkpoints work.
>>
>
> Yep, definitely:-) On the other hand I though I was seeking something
> "simple", namely correct latency under small load, that I would expect out
> of the box.
>
> What you describe is reasonable, and is more or less what I was hoping
> for, although I thought that bgwriter was involved from the start and
> checkpoint would only do what is needed in the end. My mistake.
>
>
If all you want is to avoid the write storms when fsyncs start happening on
slow storage, can you not just adjust the kernel vm.dirty* tunables to
start making the kernel write out dirty buffers much sooner instead of
letting them accumulate until fsyncs force them out all at once?

>
a.

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