Re: PROBLEM: Linux 2.6.0-test11 only lets me use 1GB out of 2GB ram.

Nick Piggin
2003-12-11T05:49:46Z

William Lee Irwin III wrote:

>On Thu, Dec 11, 2003 at 12:33:39AM -0500, Ed Sweetman wrote:
>
>>I thought highmem wasn't necesarily needed for memory <=2GB? Highmem
>>incurs some performance hits doesn't it and so the urge to move to it
>>with only 2GB is not very attractive. Anyways i'm just interested in if
>>that's the case or not since 2GB is easy to get to these days and i had
>>heard that highmem could be avoided passed the 1GB barrier.
>>
>
>You're probably thinking of 2:2 split patches.
>
>2:2 splits are at least technically ABI violations, which is probably
>why this isn't merged etc. Applications sensitive to it are uncommon.
>
>Yes, the SVR4 i386 ELF/ABI spec literally mandates 0xC0000000 as the
>top of the process address space.
>

At any rate, Raul, highmem shouldn't hurt your performance significantly
with the 2.6 kernel. If it does then send a note to the list.

Your other options are a different user/kernel split, or a 64-bit kernel,
both of which should have less overhead than highmem.