Horton

Re: Direct I/O

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Munro <thomas.munro@gmail.com>, Andrew Dunstan <andrew@dunslane.net>, Heikki Linnakangas <hlinnaka@iki.fi>, Noah Misch <noah@leadboat.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, pgsql-hackers@postgresql.org
Date: 2023-04-08T21:42:14Z
Lists: pgsql-hackers 
Hi,

On 2023-04-08 17:31:02 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2023-04-08 17:10:19 -0400, Tom Lane wrote:
> > It's also odd that it's just crake having the issue. It's just a linux host,
> > afaics.
> 
> Indeed.  I'm guessing from the compiler version that it's Fedora 37 now

The 15 branch says:

hostname = neoemma
uname -m = x86_64
uname -r = 6.2.8-100.fc36.x86_64
uname -s = Linux
uname -v = #1 SMP PREEMPT_DYNAMIC Wed Mar 22 19:14:19 UTC 2023

So at least the kernel claims to be 36...


> (the lack of such basic information in the meson configuration output
> is pretty annoying).

Yea, I was thinking yesterday that we should add uname output to meson's
configure (if available). I'm sure we can figure out a reasonably fast windows
command for the version, too.


> I've been trying to repro it here on an F37 box, with no success, suggesting
> that it's very timing sensitive.  Or maybe it's inside a VM and that
> matters?

Could also be filesystem specific?

Greetings,

Andres Freund

Commits

  1. Rename hook functions for debug_io_direct to match variable name.

  2. Rename io_direct to debug_io_direct.

  3. Skip the 004_io_direct.pl test if a pre-flight check fails.

  4. Use higher wal_level for 004_io_direct.pl.

  5. Skip \password TAP test on old IPC::Run versions

  6. Add io_direct setting (developer-only).

  7. Introduce PG_IO_ALIGN_SIZE and align all I/O buffers.

  8. Add palloc_aligned() to allow aligned memory allocations

  9. initdb: When running CREATE DATABASE, use STRATEGY = WAL_COPY.