Re: Machine's high load when HIGHMEM is enabled

Dave Jones
2002-11-06T17:05:05Z

On Wed, Nov 06, 2002 at 08:51:17AM -0800, Andrew Morton wrote:
> For some reason your mtrr table was not covering the last 32 megabytes
> of memory. Probably you could also have fixed this by altering the
> mtrr settings. See Documentation/mtrr.txt in the kernel source tree.

I've seen this happen on systems with onboard graphics cards
that share system RAM as video RAM. The end result is that Linux
sees an amount of mem that isn't a power of two.

In extreme cases, the BIOS has done really mad things like
instead of covering the 1GB with 1 MTRR, it splits it into
7 MTRRs covering 512MB,256MB,128MB,64MB,32MB,16MB,8MB.
Icky.

Dave

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| Dave Jones. http://www.codemonkey.org.uk