All of lore.kernel.org
 help / color / mirror / Atom feed
From: fgenfb@yahoo.com (Harm Hanemaaijer)
To: linux-arm-kernel@lists.infradead.org
Subject: Call for testing/opinions: Optimized memset/memcpy
Date: Sun, 14 Jul 2013 11:19:27 +0000 (UTC)	[thread overview]
Message-ID: <loom.20130714T130546-799@post.gmane.org> (raw)
In-Reply-To: 20130713164840.GC28473@gallifrey

Dr. David Alan Gilbert <gilbertd <at> treblig.org> writes:
> 
> Maybe neon is worth a try these days (although be careful of platforms
> like Tegra 2 that doens't have it); there was a recent patch that enabled
> use in the kernel (I think for some RAID use). The downside is it's
> supposed to be quite power hungry.
> 

As it turns out, NEON isn't too hard to implement. I have added NEON support
to copy_page, memset, memzero, and memcpy (both for the aligned and unaligned
case) in my userspace testing environment. It gives a nice boost (ranging
from 10% for copy_page to >30% for unaligned memcpy on a Cortex A8), which
can potentially be more on other cores. Although I have not tested a live
kernel yet, it looks like NEON can be used fairly transparently #ifdefed on
the CONFIG_NEON kernel definition as long as only the lower end of the
NEON/vfp register file is clobbered (although this needs verification).

  parent reply	other threads:[~2013-07-14 11:19 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-13 15:51 Call for testing/opinions: Optimized memset/memcpy Harm Hanemaaijer
2013-07-13 16:48 ` Dr. David Alan Gilbert
2013-07-13 21:13   ` Harm Hanemaaijer
2013-07-15 13:15     ` Catalin Marinas
2013-07-14 11:19   ` Harm Hanemaaijer [this message]
2013-07-14 11:32     ` Dr. David Alan Gilbert
2013-07-14 11:37     ` Ard Biesheuvel
2013-07-14 13:13       ` Russell King - ARM Linux
2013-07-14 13:33       ` Harm Hanemaaijer
2013-07-14 14:09         ` Ard Biesheuvel
2013-07-14 14:32           ` Russell King - ARM Linux
2013-07-13 17:24 ` Willy Tarreau
2013-07-13 21:51   ` Harm Hanemaaijer
2013-07-14  6:13     ` Willy Tarreau
2013-07-14 11:00       ` Harm Hanemaaijer
2013-07-14 13:09         ` Russell King - ARM Linux
2013-07-14 13:59           ` Harm Hanemaaijer
2013-07-14 15:21         ` Siarhei Siamashka

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=loom.20130714T130546-799@post.gmane.org \
    --to=fgenfb@yahoo.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.