From: Tulio Magno Quites Machado Filho <tuliom@ascii.art.br>
To: Shawn Landden <shawn@git.icu>, Joseph Myers <joseph@codesourcery.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] powerpc: add libmvec implementations of log and logf
Date: Thu, 09 May 2019 16:58:02 -0300 [thread overview]
Message-ID: <878svfqu2d.fsf@linux.ibm.com> (raw)
In-Reply-To: <CA+49okrZHo5kL0MLOTnoR8Fr=KbBDHZfj7kOWB0PnMJ_MHxETA@mail.gmail.com>
Shawn Landden <shawn@git.icu> writes:
> When I first looked at Bert's patch I saw all the scalar code for the
> special path and thought it wasn't a real vector implementation.
> Otherwise I wouldn't have tried to compete with him.
>
> HOWEVER, once I fixed the bugs in my benchmark programs, there is no
> performance advantage of doing either log or logf with vector
> operation, at least on this power 9 VPS---either mine or Bert's
> patches. I think this is because they require too many table lookups
> for the constants, and Power ISA 3.0 lacks both a gather instruction,
> and a permutexvar instruction, both of which could be used to
> vectorize these table lookups. (shufflevector can't do it)
Base on this information and considering that you haven't a FSF copyright
assignment, which means I can't look at your patch, I plan to merge Bert's
patches.
Thank you!
--
Tulio Magno
next prev parent reply other threads:[~2019-05-09 19:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-05 20:34 [RFC][PATCH] powerpc: add libmvec implementations of log and logf Shawn Landden
2019-05-05 20:53 ` Shawn Landden
2019-05-06 20:32 ` [PATCH] " Shawn Landden
2019-05-07 15:21 ` Joseph Myers
2019-05-08 23:04 ` Shawn Landden
2019-05-09 19:58 ` Tulio Magno Quites Machado Filho [this message]
2019-05-10 1:00 ` Shawn Landden
2019-05-10 19:16 ` Tulio Magno Quites Machado Filho
2019-05-13 16:50 ` Joseph Myers
2019-05-13 21:28 ` Shawn Landden
2019-05-17 14:59 ` Shawn Landden
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/libc/involved.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=878svfqu2d.fsf@linux.ibm.com \
--to=tuliom@ascii.art.br \
--cc=joseph@codesourcery.com \
--cc=libc-alpha@sourceware.org \
--cc=shawn@git.icu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).