Justin Piszcz írta:


On Wed, 30 May 2007, Zoltan Boszormenyi wrote:

Hi,

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.

I saw a similar effect on a P5 board that could
only cache 64MB of memory a long time ago.
Putting more memory into it made the machine slower
and e.g. made the sym2 driver giving up at initialization.
Maybe it's a modern reincarnation of the problem?

Best regards,
Zoltán Böszörményi


I see, so Intel 965 motherboards do not work with 8GB of memory? Or is this a Linux issue?

It was certainly a mainboard problem, the same system worked well
on another board with a more capable L2 cache controller.
Or on PPro/P-II boards.

I have an Intel Case ID open 225446 but so far we have not gotten anywhere with this problem. Currently I have 8GB in the machine and boot with mem=4096M. Was there any type of fix? Any recommendations as to what I can do? Continue to speak with Intel? Or perhaps someone with more knowledge of the kernel and chime in as to what exactly is happening here?

Justin.

I think continue to talk Intel and with the kernel guys,
I don't have experience with machines with so much memory (yet).

Best regards,
Zoltán Böszörményi

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