Horton

Re: [PATCH] Hex-coding optimizations using SVE on ARM.

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, "Chiranmoy.Bhattacharya@fujitsu.com" <Chiranmoy.Bhattacharya@fujitsu.com>, "Devanga.Susmitha@fujitsu.com" <Devanga.Susmitha@fujitsu.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, "Ragesh.Hajela@fujitsu.com" <Ragesh.Hajela@fujitsu.com>
Date: 2025-01-15T06:57:26Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Optimize hex_encode() and hex_decode() using SIMD.

  2. Speed up hex_encode with bytewise lookup

Attachments

On Tue, Jan 14, 2025 at 11:57 PM Nathan Bossart
<nathandbossart@gmail.com> wrote:
>
> On Tue, Jan 14, 2025 at 12:59:04AM -0500, Tom Lane wrote:
> > John Naylor <johncnaylorls@gmail.com> writes:
> >> We can do about as well simply by changing the nibble lookup to a byte
> >> lookup, which works on every compiler and architecture:
>
> Nice.  I tried enabling auto-vectorization and loop unrolling on top of
> this patch, and the numbers looked the same.  I think we'd need CPU
> intrinsics or an even bigger lookup table to do any better.

Thanks for looking further! Yeah, I like that the table is still only 512 bytes.

> > I didn't attempt to verify your patch, but I do prefer addressing
> > this issue in a machine-independent fashion.  I also like the brevity
> > of the patch (though it could do with some comments perhaps, not that
> > the existing code has any).
>
> +1

Okay, I added a comment. I also agree with Michael that my quick
one-off was a bit hard to read so I've cleaned it up a bit. I plan to
commit the attached by Friday, along with any bikeshedding that
happens by then.

--
John Naylor
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