Re: Why we are going to have to go DirectIO - Mailing list pgsql-hackers

From Merlin Moncure
Subject Re: Why we are going to have to go DirectIO
Date
Msg-id CAHyXU0weQ8XAKNQG+M4nz3c7kTF+J5r4zforZt3aZKVJb_zTtg@mail.gmail.com
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In response to Re: Why we are going to have to go DirectIO  (Jonathan Corbet <corbet@lwn.net>)
List pgsql-hackers
On Wed, Dec 4, 2013 at 2:31 PM, Jonathan Corbet <corbet@lwn.net> wrote:
> For those interested in the details... (1) It's not quite 50/50, that's one
> bound for how the balance is allowed to go.  (2) Anybody trying to add
> tunables to the kernel tends to run into resistance.  Exposing thousands of
> knobs tends to lead to a situation where you *have* to be an expert on all
> those knobs to get decent behavior out of your system.  So there is a big
> emphasis on having the kernel tune itself whenever possible.  Here is a
> situation where that is not always happening, but a fix (which introduces
> no knob) is in the works.

I think there are interesting parallels here with the 'query plan
hints' debate.  In both cases I think the conservative voices are
correct: better not to go crazy adding knobs.

merlin



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