Horton

Re: add AVX2 support to simd.h

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Ants Aasma <ants@cybertec.at>, pgsql-hackers@postgresql.org
Date: 2024-03-19T03:16:01Z
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. Improve style of pg_lfind32().

  2. Fix compiler warning for pg_lfind32().

  3. Micro-optimize pg_lfind32().

  4. Introduce helper SIMD functions for small byte arrays

  5. Optimize xid/subxid searches in XidInMVCCSnapshot().

On Tue, Mar 19, 2024 at 10:03:36AM +0700, John Naylor wrote:
> I took a brief look, and 0001 isn't quite what I had in mind. I can't
> quite tell what it's doing with the additional branches and "goto
> retry", but I meant something pretty simple:

Do you mean 0002?  0001 just adds a 2-register loop for remaining elements
once we've exhausted what can be processed with the 4-register loop.

> - if short, do one element at a time and return

0002 does this.

> - if long, do one block unconditionally, then round the start pointer
> up so that "end - start" is an exact multiple of blocks, and loop over
> them

0002 does the opposite of this.  That is, after we've completed as many
blocks as possible, we move the iterator variable back to "end -
block_size" and do one final iteration to cover all the remaining elements.

-- 
Nathan Bossart
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