From: | KONDO Mitsumasa <kondo(dot)mitsumasa(at)lab(dot)ntt(dot)co(dot)jp> |
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To: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Optimize kernel readahead using buffer access strategy |
Date: | 2013-11-18 04:07:52 |
Message-ID: | 52899298.9030907@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
(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
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