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
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