From: Michael Paquier <michael@paquier.xyz>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Xuneng Zhou <xunengzhou@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: per backend WAL statistics
Date: Tue, 11 Mar 2025 09:06:27 +0900
Message-ID: <Z89-gxOVxtEP_w9d@paquier.xyz> (raw)
In-Reply-To: <Z87SetO+E/QOayNP@ip-10-97-1-34.eu-west-3.compute.internal>
References: <Z8hLi1dGfPFc8AYy@ip-10-97-1-34.eu-west-3.compute.internal>
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<Z87SetO+E/QOayNP@ip-10-97-1-34.eu-west-3.compute.internal>
On Mon, Mar 10, 2025 at 11:52:26AM +0000, Bertrand Drouvot wrote:
> Hi,
>
> On Mon, Mar 10, 2025 at 04:46:53PM +0900, Michael Paquier wrote:
> > On Sat, Mar 08, 2025 at 07:53:04AM +0000, Bertrand Drouvot wrote:
> > > That would not be an issue should we only access the struct
> > > fields in the code, but that's not the case as we're making use of
> > > pg_memory_is_all_zeros() on it.
> >
> > It does not hurt to keep it as it is, honestly.
>
> I believe that's worse than before actually. Before padding bytes would "probably"
> be set to zeros while now it's certainly not always the case. I think that
> we already removed this (see comments === 4 in [1]).
We still apply the memset(), and the initialization is actually the
same.
> I think it's better to check for:
>
> if (pg_memory_is_all_zeros(&PendingBackendStats.pending_io,
> sizeof(struct PgStat_PendingIO)))
>
> like in the attached. Or check on "backend_has_iostats" (if 0002 in [2] goes in).
Yes, restricting this check to apply on the PgStat_PendingIO makes
sense.
> I think we can use "else if" here (done in the attached) as it's not needed if
> has_pending_data is already set to true.
Still the blocks with the comments become a bit weird if formulated
this way. Kept this one the same as v17.
And I guess that we're OK here, so applied. That should be the last
one.
--
Michael
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To: pgsql-hackers@postgresql.org
Cc: michael@paquier.xyz, bertranddrouvot.pg@gmail.com, andres@anarazel.de, xunengzhou@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: per backend WAL statistics
In-Reply-To: <Z89-gxOVxtEP_w9d@paquier.xyz>
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