Re: O_DIRECT for relations and SLRUs (Prototype) - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: O_DIRECT for relations and SLRUs (Prototype)
Date
Msg-id 20190116015428.GK1433@paquier.xyz
Whole thread Raw
In response to Re: O_DIRECT for relations and SLRUs (Prototype)  (Maksim Milyutin <milyutinma@gmail.com>)
List pgsql-hackers
On Tue, Jan 15, 2019 at 07:40:12PM +0300, Maksim Milyutin wrote:
> Could you specify all cases when buffers will not be aligned with BLCKSZ?
>
> AFAIC shared and temp buffers are aligned. And what ones are not?

SLRU buffers are not aligned with the OS pages (aka alignment with
4096 at least).  There are also a bunch of code paths where the callers
of mdread() or mdwrite() don't do that, which makes a correct patch
more invasive.
--
Michael

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