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Re: vmalloc cached space..

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: vmalloc cached space..
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Wed, 16 Apr 2003 15:35:30 +0200 (MET DST)
Cc: Ashish anand <ashish.anand@inspiretech.com>, linux-mips@linux-mips.org
In-reply-to: <20030416135756.B29679@linux-mips.org>
Organization: Technical University of Gdansk
Original-recipient: rfc822;linux-mips@linux-mips.org
Reply-to: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Sender: linux-mips-bounce@linux-mips.org
On Wed, 16 Apr 2003, Ralf Baechle wrote:

> > 2. i should use vmalloc_prot (size, PAGE_KERNEL_UNCACHED) in umap.c.
> 
> Uncached memory access is rarely necessary and so _extremly_ slow that it
> should be avoided at almost any price.  Maybe you should describe what
> you're trying to achieve, then let's see if there's a better suggestion
> we can make.

 In particular using cached accesses for stores and then doing writebacks
(plus invalidates if necessary) is still faster with WB caches. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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