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.


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