| From: | John Naylor <john(dot)naylor(at)enterprisedb(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jelte Fennema <Jelte(dot)Fennema(at)microsoft(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net> |
| Subject: | Re: [PATCH] Optimize json_lex_string by batching character copying |
| Date: | 2022-07-12 06:57:48 |
| Message-ID: | CAFBsxsGzaaGLF=Nuq61iRXTyspbO9rOjhSqFN=V6ozzmta5mXg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Jul 11, 2022 at 11:07 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> I wonder if we can add a somewhat more general function for scanning until
> some characters are found using SIMD? There's plenty other places that
could
> be useful.
In simple cases, we could possibly abstract the entire loop. With this
particular case, I imagine the most approachable way to write the loop
would be a bit more low-level:
while (p < end - VECTOR_WIDTH &&
!vector_has_byte(p, '\\') &&
!vector_has_byte(p, '"') &&
vector_min_byte(p, 0x20))
p += VECTOR_WIDTH
I wonder if we'd lose a bit of efficiency here by not accumulating set bits
from the three conditions, but it's worth trying.
--
John Naylor
EDB: http://www.enterprisedb.com
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