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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-hackers@lists.postgresql.org, Andres Freund <andres@anarazel.de>
Subject: Re: Add per-backend AIO statistics
Date: Wed, 8 Jul 2026 08:15:26 +0000
Message-ID: <ak4HHsXZOrVfRzKc@bdtpg> (raw)
In-Reply-To: <ak3zpA2HHh5CxQK8@paquier.xyz>
References: <akzcq9jtWK5C92g1@bdtpg>
	<ak3zpA2HHh5CxQK8@paquier.xyz>

Hi,

On Wed, Jul 08, 2026 at 03:52:20PM +0900, Michael Paquier wrote:
> On Tue, Jul 07, 2026 at 11:02:03AM +0000, Bertrand Drouvot wrote:
> > 1/ pg_aios that lists all AIO handles that are currently in use. That shows
> > what's happening right now, but not what has happened.
> > 
> > 2/ pg_stat_get_backend_io() that shows how much IO was done, but not how it
> > was done. There's no way to see whether IOs ran synchronously or
> > asynchronously, whether a backend was stalling on handle exhaustion, or how
> > completions are distributed across backends.
> 
> While the information may be useful,

Thanks for looking at it!

> Andres is usually able to catch bottlenecks that everybody else is
> unable to see, so perhaps checking with him the location of these
> extra function calls would be a good first step.  Your proposal goes
> down to pgaio_io_stage(), pgaio_io_process_completion() and
> pgaio_submit_staged() to track these counter increments.

yeah, and also to 1/ confirm that I did understand this area of the AIO code
correctly and 2/ see if other counters could make sense.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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