Re: Direct I/O - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: Direct I/O
Date
Msg-id 61afddef-c1c1-bba8-ee0d-8c0f53c83039@dunslane.net
Whole thread Raw
In response to Re: Direct I/O  (Thomas Munro <thomas.munro@gmail.com>)
Responses Re: Direct I/O  (Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>)
List pgsql-hackers


On 2023-04-12 We 01:48, Thomas Munro wrote:
On Wed, Apr 12, 2023 at 3:04 PM Thomas Munro <thomas.munro@gmail.com> wrote:
On Wed, Apr 12, 2023 at 2:56 PM Christoph Berg <myon@debian.org> wrote:
I'm hitting a panic in t_004_io_direct. The build is running on
overlayfs on tmpfs/ext4 (upper/lower) which is probably a weird
combination but has worked well for building everything over the last
decade. On Debian unstable:

PANIC:  could not open file "pg_wal/000000010000000000000001": Invalid argument
... I have a new idea:  perhaps it is possible to try
to open a file with O_DIRECT from perl, and if it fails like that,
skip the test.  Looking into that now.
I think I have that working OK.  Any Perl hackers want to comment on
my use of IO::File (copied from examples on the internet that showed
how to use O_DIRECT)?  I am not much of a perl hacker but according to
my package manager, IO/File.pm came with perl itself.  And the Fcntl
eval trick that I copied from File::stat, and the perl-critic
suppression that requires?


I think you can probably replace a lot of the magic here by simply saying


if (Fcntl->can("O_DIRECT")) ...


cheers


andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

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