Re: 2.4: mylex and > 2GB RAM

[Hank Leininger]

On 2003-12-08, Per Buer <perbu () linpro ! no> wrote:

> I have an Supermicro Superserver (wow!) 8040 or 8060 with a two Intel
> Xeon (p3-based with 1MB cache) and a Mylex AcceleRAID 352. We recently
> upgraded from 2 to 4GB of memory.

> There seems to a problem with IO and high memory. Suddenly IO
> performance will degrade dramatically (throughput of about 50KB/s).
> Booting the machine with "mem=2048" remedies this.

> We have tried replacing the memory with another make - no luck.

You don't mention the kernel version--I'm guessing a 2.4.x?

This doesn't necessarily help you, but: I haven't seen that on a dual P3
with 3GB of RAM (configured with CONFIG_HIGHMEM4G=y, CONFIG_HIGHMEM=y and
CONFIG_HIGHIO=y) and an AcceleRAID 352, in 2.4.22.  (I did get oopses with
this card and 3GB in 2.2 kernel days, using the old bigmem patches for 2.2.
I didn't stick around to find out whose fault it was though, just dropped
back to 2GB)

So, try verifying you've got CONFIG_HIGHIO=y, and out of curiosity you
could try mem=3072, but if that doesn't help I'd suspect the motherboard. 
This box is... um... an Intel serverworks board whose exact model number
escapes me at the moment.

--
Hank Leininger <hlein@xxxxxxxxxxxxxxxxxxxx> 
  
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