Re: Kernel 2.6.21.3 does not work with 8GB of RAM on Intel 965WH motherboards.

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Wed, 30 May 2007, Justin Piszcz wrote:

>
>
> On Tue, 29 May 2007, Robert Hancock wrote:
>
>> Justin Piszcz wrote:
>>> Short Description of Problem:
>>> Linux 2.6.21.3 does not run properly with 8GB of ram on the Intel 965WH 
>>> motherboard.
>>> I found it interesting in make menuconfig on x86_64 there is no 4GB/64GB
>>> options in the kernel that I remember seeing in 32bit.
>> 
>> That's because that option is not applicable in 64-bit mode.
>> 
>> Can you send your full dmesg output from the 8GB bootup?
>> 
>> -- 
>> Robert Hancock      Saskatoon, SK, Canada
>> To email, remove "nospam" from hancockr@nospamshaw.ca
>> Home Page: http://www.roberthancock.com/
>> 
>
> Kernel dmesg attached from 8GB bootup.
>
> Robert, how come the option is not applicable in 64-bit mode? If I want to 
> use all 8GB of memory I need to run a 32-bit kernel?
>
> Justin.

Look at how slow the raid benchmarks are in dmesg with 8GB of memory!

[   59.592560] raid6: using algorithm sse2x4 (476 MB/s)
[   59.597558] raid5: using function: generic_sse (56.000 MB/sec)

Yikes!

With mem=4096M:
[   60.336352] raid6: using algorithm sse2x4 (6804 MB/s)
[   60.341345] raid5: using function: generic_sse (8552.000 MB/sec)

What is going on here?

Justin.