From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Jeff Garzik <jgarzik@pobox.com>, Andrew Morton <akpm@osdl.org>,
manfred@colorfullife.com,
Linux Kernel List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] optimize ia32 memmove
Date: Tue, 30 Dec 2003 02:17:59 -0800 [thread overview]
Message-ID: <1072779479.16344.95.camel@ixodes.goop.org> (raw)
In-Reply-To: <Pine.LNX.4.58.0312300152250.2065@home.osdl.org>
On Tue, 2003-12-30 at 01:58, Linus Torvalds wrote:
> But then anything that does the loads in ascending order is still ok, so
> it shouldn't matter - by the time "dest" has been overwritten, the source
> data has already been read. And all the "memcpy()" implementations had
> better do that anyway, in order to get nice memory access patterns. "rep
> movsl" certainly does.
A PPC memcpy may end up clearing the destination before reading the
source (using the cache-line zeroing instruction, to prevent the
destination from being spuriously read to populate the cache line).
J
next prev parent reply other threads:[~2003-12-30 10:18 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 ` 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 [this message]
2003-12-30 11:12 ` Manfred Spraul
2003-12-30 20:17 ` H. Peter Anvin
2003-12-30 10:21 ` Ed Sweetman
2003-12-30 10:37 ` Andrew Morton
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