From: Dan Malek <dan@embeddededge.com>
To: Joakim Tjernlund <Joakim.Tjernlund@lumentis.se>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: lmw and stmw instructions not used copy functions
Date: Wed, 19 Feb 2003 23:06:38 -0500 [thread overview]
Message-ID: <3E54544E.2040804@embeddededge.com> (raw)
In-Reply-To: 004f01c2d861$c6cdab30$020120b0@jockeXP
Joakim Tjernlund wrote:
> I noticed that the lmw and stmw instructions are not used in copy_page(), clear_page() etc.
> Aren't these instructions faster than a bunch of lwz/stw?
Motorola doesn't guarantee these are any faster, and most documentation indicates
they are likely to be slower. If you look closely, you may notice that not
too many places can utilize these instructions, and often the load or store
is done to take advantages of some pipeline optimizations with comparisons
to values in well known registers.
-- Dan
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2003-02-20 4:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-14 21:24 question about first packet received by mpc8260 Steven Blakeslee
2003-02-19 21:56 ` lmw and stmw instructions not used copy functions Joakim Tjernlund
2003-02-20 4:06 ` Dan Malek [this message]
2003-02-21 8:31 ` Joakim Tjernlund
2003-02-21 12:48 ` Dan Malek
2003-02-21 13:54 ` Joakim Tjernlund
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