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From: Marvin Justice <mjustice@austin.rr.com>
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To: "H. Peter Anvin" <hpa@zytor.com>, mjustice@austin.rr.com
Subject: Re: highmem question
Date: Fri, 7 Dec 2001 19:53:47 -0600
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>
> The problem is that in the x86 architecture you don't have any reasonable
> way of addressing the physical address space, so you need to map it into
> the virtual address space.  You end up with a shortage of virtual address
> space.

Isn't this still just an artifact of the default 1:3 kernel/user virtual 
address space split? I've never tried it myself but isn't there a 2:2 patch 
available that has the effect of moving the highmem boundary up?

>
> There is no way of fixing it.

All I know is that a streaming io app I was playing with showed a drastic 
performance hit when the kernel was compiled with CONFIG_HIGHMEM. On W2K we 
saw no slowdown with 2 or even 4GB of RAM so I think solutions must exist.

Marvin
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