From: "H. Peter Anvin" <hpa@zytor.com>
To: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] optimize ia32 memmove
Date: 30 Dec 2003 12:17:59 -0800 [thread overview]
Message-ID: <bssmhn$bt$1@cesium.transmeta.com> (raw)
In-Reply-To: 3FF15DAB.8080203@colorfullife.com
Followup to: <3FF15DAB.8080203@colorfullife.com>
By author: Manfred Spraul <manfred@colorfullife.com>
In newsgroup: linux.dev.kernel
>
> AMD recommends to perform bulk copies backwards: That defeats the hw
> prefecher, and results in even better access patterns. Doesn't matter in
> this case, memmove is never used for bulk copies.
>
That's also a microoptimization for one particular microarchitecture
*bug*. Hardware prefetchers are going omnidirectional going forward.
Additionally, nearly all bulk copies are performed forward (DF=0) in
existing codebases.
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
If you send me mail in HTML format I will assume it's spam.
"Unix gives you enough rope to shoot yourself in the foot."
Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64
next prev parent reply other threads:[~2003-12-30 20:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200312300713.hBU7DGC4024213@hera.kernel.org>
2003-12-30 7:32 ` [PATCH] optimize ia32 memmove Jeff Garzik
2003-12-30 7:51 ` Andrew Morton
2003-12-30 7:56 ` Jeff Garzik
2003-12-30 8:11 ` Andrew Morton
2003-12-30 8:11 ` Andreas Dilger
2003-12-30 10:05 ` Linus Torvalds
2003-12-30 9:58 ` Linus Torvalds
2003-12-30 10:17 ` Jeremy Fitzhardinge
2003-12-30 11:12 ` Manfred Spraul
2003-12-30 20:17 ` H. Peter Anvin [this message]
2003-12-30 10:21 ` Ed Sweetman
2003-12-30 10:37 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='bssmhn$bt$1@cesium.transmeta.com' \
--to=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.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.