From: Nathan Bossart <nathandbossart@gmail.com>
To: Chiranmoy.Bhattacharya@fujitsu.com <Chiranmoy.Bhattacharya@fujitsu.com>
Cc: Devanga.Susmitha@fujitsu.com <Devanga.Susmitha@fujitsu.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Cc: Ragesh.Hajela@fujitsu.com <Ragesh.Hajela@fujitsu.com>
Subject: Re: [PATCH] Hex-coding optimizations using SVE on ARM.
Date: Fri, 10 Jan 2025 14:46:45 -0600
Message-ID: <Z4GHNfhRKuA0r_Wn@nathan> (raw)
In-Reply-To: <Z4E-5oQGux-2R4iL@nathan>
References: <OSZPR01MB8499D4884C4541159FA00ECC8B132@OSZPR01MB8499.jpnprd01.prod.outlook.com>
<Z4AUr-Y-TPaqtg0y@nathan>
<OSBPR01MB26648F7B60A543069C75EC43971C2@OSBPR01MB2664.jpnprd01.prod.outlook.com>
<Z4E-5oQGux-2R4iL@nathan>
On Fri, Jan 10, 2025 at 09:38:14AM -0600, Nathan Bossart wrote:
> On Fri, Jan 10, 2025 at 11:10:03AM +0000, Chiranmoy.Bhattacharya@fujitsu.com wrote:
>> We tried auto-vectorization and observed no performance improvement.
>
> Do you mean that the auto-vectorization worked and you observed no
> performance improvement, or the auto-vectorization had no effect on the
> code generated?
I was able to get auto-vectorization to take effect on Apple clang 16 with
the following addition to src/backend/utils/adt/Makefile:
encode.o: CFLAGS += ${CFLAGS_VECTORIZE} -mllvm -force-vector-width=8
This gave the following results with your hex_encode_test() function:
buf | HEAD | patch | % diff
-------+-------+-------+--------
16 | 21 | 16 | 24
64 | 54 | 41 | 24
256 | 138 | 100 | 28
1024 | 441 | 300 | 32
4096 | 1671 | 1106 | 34
16384 | 6890 | 4570 | 34
65536 | 27393 | 18054 | 34
This doesn't compare with the gains you are claiming to see with
intrinsics, but it's not bad for a one line change. I bet there are ways
to adjust the code so that the auto-vectorization is more effective, too.
--
nathan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, Chiranmoy.Bhattacharya@fujitsu.com, Devanga.Susmitha@fujitsu.com, Ragesh.Hajela@fujitsu.com
Subject: Re: [PATCH] Hex-coding optimizations using SVE on ARM.
In-Reply-To: <Z4GHNfhRKuA0r_Wn@nathan>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox