From: Andres Freund <andres@anarazel.de>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Greg Stark <gsstark@mit.edu>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org, Michael Clemmons <glassresistor@gmail.com>
Cc: Hannu Krosing <hannu@2ndquadrant.com>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Subject: Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: Sat, 6 Feb 2010 13:03:50 +0100
Message-ID: <201002061304.01682.andres@anarazel.de> (raw)
In-Reply-To: <4B6CF822.9010608@2ndquadrant.com>
References: <4427a97a0912101235x3ade510blcc00d5ce9883c6b6@mail.gmail.com>
<4B698605.50506@anarazel.de>
<4B6CF822.9010608@2ndquadrant.com>
On Saturday 06 February 2010 06:03:30 Greg Smith wrote:
> Andres Freund wrote:
> > On 02/03/10 14:42, Robert Haas wrote:
> >> Well, maybe we should start with a discussion of what kernel calls
> >> you're aware of on different platforms and then we could try to put an
> >> API around it.
> >
> > In linux there is sync_file_range. On newer Posixish systems one can
> > emulate that with mmap() and msync() (in batches obviously).
> >
> > No idea about windows.
> The effective_io_concurrency feature had proof of concept test programs
> that worked using AIO, but actually following through on that
> implementation would require a major restructuring of how the database
> interacts with the OS in terms of reads and writes of blocks. It looks
> to me like doing something similar to sync_file_range on Windows would
> be similarly difficult.
Looking a bit arround it seems one could achieve something approximediately
similar to pg_prepare_fsync() by using
CreateFileMapping && MapViewOfFile && FlushViewOfFile
If I understand it correctly that will flush, but not wait. Unfortunately you
cant event make it wait, so its not possible to implement sync_file_range or
similar fully.
Andres
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Subject: Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
In-Reply-To: <201002061304.01682.andres@anarazel.de>
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