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In-Reply-To: <19422eb3-54dc-4afb-8046-5eee906edacd@iki.fi>
From: Thomas Munro <thomas.munro@gmail.com>
Date: Fri, 25 Apr 2025 13:31:46 +1200
Message-ID: <CA+hUKGLM7j65kEf9p_v11s+aonjZztyS_3xmAOeuzmcrOQ+P8w@mail.gmail.com>
Subject: Re: AIX support
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Srirama Kucherlapati <sriram.rk@in.ibm.com>, 
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, 
	Bruce Momjian <bruce@momjian.us>, Peter Eisentraut <peter@eisentraut.org>, 
	Alvaro Herrera <alvherre@alvh.no-ip.org>, Laurenz Albe <laurenz.albe@cybertec.at>, 
	Noah Misch <noah@leadboat.com>, Michael Paquier <michael@paquier.xyz>, 
	Andres Freund <andres@anarazel.de>, "tvk1271@gmail.com" <tvk1271@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, 
	Tristan Partin <tristan@neon.tech>, wenhui qiu <qiuwenhuifx@gmail.com>, 
	"postgres-ibm-aix@wwpdl.vnet.ibm.com" <postgres-ibm-aix@wwpdl.vnet.ibm.com>
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On Mon, Apr 7, 2025 at 10:04=E2=80=AFPM Heikki Linnakangas <hlinnaka@iki.fi=
> wrote:
> I'm surprised how big the difference is, because I actually expected the
> compiler to detect the memory-zeroing loop and replace it with some
> fancy vector instructions (does powerpc have any?).

It certainly does, and we've played with explicit AltiVec
vectorisation before with the idea that our abstraction over x86 and
ARM instructions could be extended to POWER, but that was just trying
stuff and learning while wondering if those abstractions are general
enough and how well all the instructions match up.  No one with modern
hardware and a vested interest has seriously investigated it.  That's
independent of automatic vectorisation done by the compiler or libc,
and I guess it would not really be AIX-specific since it would also
apply to Linux on POWER.  One of those patches is linked from this
small list of "ideas for a future PostgreSQL/AIX maintainer":

https://wiki.postgresql.org/wiki/AIX