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Date: Wed, 5 Mar 2003 05:10:56 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: Michael Vergoz <mvergoz@sysdoor.com>
Cc: alan@lxorguk.ukuu.org.uk, timothy.a.reed@lmco.com,
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Subject: Re: High Mem Options
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On Wed, 5 Mar 2003 04:57:47 -0800, William Lee Irwin III wrote:
>> The cpu can't look at more than 4GB at a time.
>> Protected mode doesn't help this, turning paging on and PAE on does.
>> What it can do is point pagetables at different 4GB subsets of memory.
>> c.f. kmap_atomic() for how to window around using what's actually a
>> very small set of PTE's.

On Wed, Mar 05, 2003 at 02:02:57PM +0100, Michael Vergoz wrote:
> Right, but if the pagetable pointing to a different 4GB subsets of
> memory. The performance of the system can be disastrous, not?

Well, the TLB gets blown away at the drop of a hat. Things just have
lower scaling factors with respect to memory than say, 64-bit, though
Linux doesn't do anything about TLB coverage on 64-bit yet anyway.

It might be better to take this one to kernelnewbies@nl.linux.org


-- wli
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