Re: highmem question

Marvin Justice (mjustice@austin.rr.com)
Fri, 7 Dec 2001 19:53:47 -0600


>
> 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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