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From: Nathan Bossart <nathandbossart@gmail.com>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Ants Aasma <ants@cybertec.at>
Cc: pgsql-hackers@postgresql.org
Subject: Re: add AVX2 support to simd.h
Date: Thu, 21 Mar 2024 13:38:23 -0500
Message-ID: <20240321183823.GA1800896@nathanxps13> (raw)
In-Reply-To: <20240321170944.GA1767527@nathanxps13>
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	<20240319031601.GA828141@nathanxps13>
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	<20240321170944.GA1767527@nathanxps13>

On Thu, Mar 21, 2024 at 12:09:44PM -0500, Nathan Bossart wrote:
> On Thu, Mar 21, 2024 at 11:30:30AM +0700, John Naylor wrote:
>> Further, now that the algorithm is more SIMD-appropriate, I wonder
>> what doing 4 registers at a time is actually buying us for either SSE2
>> or AVX2. It might just be a matter of scale, but that would be good to
>> understand.
> 
> I'll follow up with these numbers shortly.

It looks like the 4-register code still outperforms the 2-register code,
except for a handful of cases where there aren't many elements.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

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