Horton

Re: Make pg_stat_io view count IOs as bytes instead of blocks

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-01-16T07:12:34Z
Lists: pgsql-hackers 
Hi,

On Thu, Jan 16, 2025 at 12:47:17AM -0500, Tom Lane wrote:
> Michael Paquier <michael@paquier.xyz> writes:
> > Not completely sure about the number of parenthesis, but I hope that
> > this should be enough (extra set around io_op):
> > +#define pgstat_is_ioop_tracked_in_bytes(io_op) \
> > +	(((unsigned int) (io_op)) < IOOP_NUM_TYPES && \
> > +	 ((unsigned int) (io_op)) >= IOOP_EXTEND)
> 
> Yeah, that's safe parenthesis-wise.  Whether it'll silence
> the warning from those old clangs remains to be seen.

Thanks for the report and the proposed "fix".

From what I can see, the above proposal does (at least) silent the warning
here (clang 5.0.1 and same as demoiselle): https://godbolt.org/z/cGosfzGne (we
can see the warning by using the current define and that the warning is gone
with the new define).

Let's see on the BF.

Regards,

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

Commits

  1. Rework macro pgstat_is_ioop_tracked_in_bytes()

  2. Remove assertion in pgstat_count_io_op()

  3. Make pg_stat_io count IOs as bytes instead of blocks for some operations

  4. Merge pgstat_count_io_op_n() and pgstat_count_io_op()