Re: Optimize kernel readahead using buffer access strategy

(2013/11/18 11:25), Claudio Freire wrote:
> On Sun, Nov 17, 2013 at 11:02 PM, KONDO Mitsumasa
> <kondo(dot)mitsumasa(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>>>> However, my patch is on the way and needed to more improvement. I am
>>>> going
>>>> to add method of controlling readahead by GUC, for user can freely select
>>>> readahed parameter in their transactions.
>>>
>>>
>>> Rather, I'd try to avoid fadvising consecutive or almost-consecutive
>>> blocks. Detecting that is hard at the block level, but maybe you can
>>> tie that detection into the planner, and specify a sequential strategy
>>> when the planner expects index-heap correlation?
>>
>> I think we had better to develop these patches in step by step each patches,
>> because it is difficult that readahead optimizetion is completely come true
>> from a beginning of one patch. We need flame-work in these patches, first.
>
> Well, problem is, that without those smarts, I don't think this patch
> can be enabled by default. It will considerably hurt common use cases
> for postgres.
Yes. I have thought as much you that defalut setting is false.
(use normal readahead as before). Next version of my patch will become these.

> But I guess we'll have a better idea about that when we see how much
> of a performance impact it makes when you run those tests, so no need
> to guess in the dark.
Yes, sure.

Regards,
--
Mitsumasa KONDO
NTT Open Source Software Center