Re: About highmem in 2.6

From: Mark de Vries
Date: Wed Feb 11 2004 - 14:14:59 EST


Dave McCracken wrote:
--On Wednesday, February 11, 2004 18:47:04 +0100 Luis Miguel García
<ktech@xxxxxxxxxx> wrote:


When I first installed 2.4, someone told me that if I had 1 gb ram it was
better to not use highmem because those extra aditional mb was not worth
the speed penalty of using the feature.

Sorry for my ignorance (and my sucking english) but must I enable highmem
now with 2.6? or have it any speed penalty althought?


I don't know if anyone has actually measured the relative performance, but
I'd expect the answer to be the same as 2.4. There is a small but
measurable performance penalty for enabling highmem which is higher than
the benefit of the extra 128 meg of memory you get when you have 1G. If
you have more than 1G it's better to enable highmem.


I've been using this patch for a while now on my box (with 1GB):
http://www.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.4/2.4.23aa1/00_3.5G-address-space-5
(kernel is 'vanilla' otherwise)

This allows you to use your full 1GB w/out highmem support.... (2G/2G user/kernel addr space split, or something..)

Anything (potentially) wrong/bad about this patch??

Is there a simmilar patch for 2.6??

Rgds,
Mark.

pls. CC in reply, I'm not on the list....
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