From: Martin Reinecke <martin@MPA-Garching.MPG.DE>
To: gcc@gcc.gnu.org
Cc: roger@eyesopen.com
Subject: Re: [BENCHMARK]-mfpmath=sse should disable x387 intrinsics
Date: Fri, 26 Nov 2004 13:02:00 -0000 [thread overview]
Message-ID: <41A70516.6080805@mpa-garching.mpg.de> (raw)
Roger Sayle wrote:
> Could you present the performance results for your testcase with
> "-mfpmath=387", "-mfpmath=sse" and "-mfpmath=sse,387"? It's relatively
> rare for "-mfpmath=sse" to be a win on a Pentium4 benchmark, and to quote
> Robert Scott Ladd from his Coyote Gulch benchmarking:
>
>From http://www.coyotegulch.com/products/acovea/acovea_4.html
>>> Much to my surprise, I have yet to find any consistent evidence that
>>> options like -mfpmath=sse improve program performance. Thus Acovea
>>> bears out my personal experience, though it does not explain why so
>>> many people continue to suggest that I should use -mfpmath=sse to
>>> generate floating-point code. If someone could suggest a good
>>> "-mfpmath=sse", I'd appreciate seeing it.
I have a real-world C++ code which gets a 10% performance gain on a P4 when compiled
with -mfpmath=sse (using the mainline compiler of 20041125). Its critical inner
loop consists of multiplications, additions and subtractions only.
Hopefully this code will be open-sourced soon; as soon as that happens, I could
contribute it as a floating-point benchmark.
Cheers,
Martin
reply other threads:[~2004-11-26 10:27 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=41A70516.6080805@mpa-garching.mpg.de \
--to=martin@mpa-garching.mpg.de \
--cc=gcc@gcc.gnu.org \
--cc=roger@eyesopen.com \
/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).