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help / color / mirror / Atom feedFrom: Alvaro Herrera <[email protected]>
To: Shankaran, Akash <[email protected]>
Cc: Nathan Bossart <[email protected]>
Cc: Noah Misch <[email protected]>
Cc: Amonson, Paul D <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: [email protected] <[email protected]>
Subject: Re: Popcount optimization using AVX512
Date: Fri, 26 Jan 2024 07:42:33 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 2024-Jan-25, Alvaro Herrera wrote:
> Finally, the matter of using ifunc as proposed by Noah seems to be still
> in the air, with no patches offered for the popcount family.
Oh, I just realized that the patch as currently proposed is placing the
optimized popcount code in the path that does not require going through
a function pointer. So the performance increase is probably coming from
both avoiding jumping through the pointer as well as from the improved
instruction.
This suggests that finding a way to make the ifunc stuff work (with good
performance) is critical to this work.
--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
"The ability of users to misuse tools is, of course, legendary" (David Steele)
https://postgr.es/m/[email protected]
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Subject: Re: Popcount optimization using AVX512
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