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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bryan Rittmeyer <bryan@staidm.org>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
	linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
	Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH] ppc32 copy_to_user dcbt fixup
Date: Sat, 13 Mar 2004 19:36:29 +1100	[thread overview]
Message-ID: <1079166987.2348.88.camel@gaston> (raw)
In-Reply-To: <20040313074934.GA15019@staidm.org>

On Sat, 2004-03-13 at 18:49, Bryan Rittmeyer wrote:
> On Sat, Mar 13, 2004 at 03:50:03PM +1100, Benjamin Herrenschmidt wrote:
> > It would be wise to make the dcbz as long as possible in "advance"
> > before the actual write to the cache line.
> 
> I guess we could try "pre-dcbz" ala the dcbt prefetch code.
> Even dcbz right before stw is probably cheaper than RAM
> loading data that will be totally overwritten. It's hard to
> lose eliminating bus I/O (especially reads).

Except if the target is already in the cache... difficult choice.

> Any comments on the dcbt prefetch patch?

Didn't have time to look at it in details yet, maybe not before
monday or tuesday

Ben



  reply	other threads:[~2004-03-13  8:41 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-03-13  4:15 [PATCH] ppc32 copy_to_user dcbt fixup Bryan Rittmeyer
2004-03-13  4:50 ` Benjamin Herrenschmidt
2004-03-13  7:49   ` Bryan Rittmeyer
2004-03-13  8:36     ` Benjamin Herrenschmidt [this message]
2004-03-15  8:38   ` Segher Boessenkool
2004-03-13  9:11 ` Eugene Surovegin
2004-03-16  1:59   ` Bryan Rittmeyer
     [not found] <1z8Na-5hH-1@gated-at.bofh.it>
2004-03-13 14:39 ` Danjel McGougan
2004-03-14 22:35   ` Bryan Rittmeyer

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