Re: [HACKERS] lseek/read/write overhead becomes visible at scale .. - Mailing list pgsql-hackers

From Andres Freund
Subject Re: [HACKERS] lseek/read/write overhead becomes visible at scale ..
Date
Msg-id 20180425203333.iga6brlp2yhzuhae@alap3.anarazel.de
Whole thread Raw
In response to Re: [HACKERS] lseek/read/write overhead becomes visible at scale ..  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] lseek/read/write overhead becomes visible at scale ..
List pgsql-hackers
On 2018-04-25 14:41:44 -0400, Robert Haas wrote:
> On Mon, Apr 16, 2018 at 2:13 AM, Andrew Gierth
> <andrew@tao11.riddles.org.uk> wrote:
> > The code that detects sequential behavior can not distinguish between
> > pread() and lseek+read, it looks only at the actual offset of the
> > current request compared to the previous one for the same fp.
> >
> >  Thomas> +1 for adopting pread()/pwrite() in PG12.
> >
> > ditto
> 
> Likewise.

+1 as well. Medium term I forsee usage of at least pwritev(), and
possibly also preadv(). Being able to write out multiple buffers at once
is pretty crucial if we ever want to do direct IO.

Greetings,

Andres Freund


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