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SubjectRe: Opteron box and 4Gb memory
On Mon, 5 Nov 2007 13:50:40 -0500, lsorense@csclub.uwaterloo.ca (Lennart Sorensen) wrote:

> On Mon, Nov 05, 2007 at 07:45:21PM +0100, J.A. Magall?n wrote:
> > Well, problem solved...
> >
> > I'm going to kill all pc assemblers in the world... Someone should teach them
> > to learn mauals before assembling anything but a power chord.
> >
> > The memory was not paired, so the motherboard was not interleaving the access.
> > With no inter-node but with inter-module interleaving, and a couple 1Gb sticks
> > for each processor now I get something like:
> >
> > cicely:~/bn> bn
> > name: cicely.cps.unizar.es
> > arch: x86-64
> > proc: 4 x x86_64 @ 2200 MHz
> > ram: 3555 Mb
> > os: unx, Linux, 2.6.23.1-desktop-1mdv
> > cc: gcc-4.3.0
> > vector size : 8 x 1024 x 1024
> > allocation: 0.02 ms
> > int scl add: .......... 60.56 ms, 138.52 Mips | 62.96 Mips /GHz
> > int scl mul: .......... 59.34 ms, 141.36 Mips | 64.26 Mips /GHz
> > flt scl add: .......... 59.01 ms, 142.16 Mflops | 64.62 Mflops/GHz
> > flt vec add: .......... 14.79 ms, 567.06 Mflops | 257.75 Mflops/GHz
> > flt scl mul: .......... 59.02 ms, 142.12 Mflops | 64.60 Mflops/GHz
> > flt vec mul: .......... 14.82 ms, 566.19 Mflops | 257.36 Mflops/GHz
> > total: 5019.86 ms
> >
> > Much better, but not like the other opteron box.
> >
> > My processors are higher than Rev E0, because the BIOS does not let me choose
> > the 'software' hole. If I activate the 'hardware hole', I see al the memory
> > I can:
> >
> > cicely:~/bn> free
> > total used free shared buffers cached
> > Mem: 3640628 214496 3426132 0 21240 84184
> > -/+ buffers/cache: 109072 3531556
> > Swap: 4200988 0 4200988
> >
> > 3.64 Gb. The rest is eaten by the graphics card, as I could read in the
> > AMD site. Don't know if mem=4096 to boot the kernel would help, even if it
> > is possible (don't think so, as it looks like a BIOS mis-feature).
> > The ram is DDR 400.
>
> The video card is stealing 300MB of ram? What for? What does the mtrr
> and e820 map look like with the hardware hole enabled?
>

(correction, this was not AMD website but SuperMicro's)

I just said the same... Board is a SuperMicro H8DCE. From the FAQ section
at supermicro:

Question
I have an H8DCE motherboard with 4 x 1GB DIMMS installed but the amount of memory displayed in the BIOS is 3.865GB and in 64-bit XP is 3.76GB. I have the hardware memory hole option enabled in BIOS (rev 1.1a). How I can get the board to count the full 4GB of memory?

Answer
The total available size depends on the PCI-e card you are using; some high-end cards may occupy more memory. For example, with a Quadro FX4500 on the H8DCE with the memory hole enabled, 4GB memory will show up as 3728MB in BIOS and 3.64GB in Windows. For some low-end PCI-e VGA cards, it may show up as 4048MB in BIOS.

Why ? Who knows...
Chipset is all nVidia. I have a GeForce 8800GTX with 768 Mb. It eats up
400Mb.

This are my settings:

BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 000000009ffd0000 (usable)
BIOS-e820: 000000009ffd0000 - 000000009ffde000 (ACPI data)
BIOS-e820: 000000009ffde000 - 00000000a0000000 (ACPI NVS)
BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
BIOS-e820: 0000000100000000 - 0000000147000000 (usable)
cicely:~# cat /proc/mtrr
reg00: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
reg01: base=0x140000000 (5120MB), size= 64MB: write-back, count=1
reg02: base=0x144000000 (5184MB), size= 32MB: write-back, count=1
reg03: base=0x146000000 (5216MB), size= 16MB: write-back, count=1
reg04: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
reg05: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
This is with BIOS set for MTRR=Discrete.
With MTRR=Continuous, the mtrr's are simpler, a full range and a non-usable
hole. Which is better for Linux ? Many separate usable zones or one big zone
and an un-usable hole ?

BTW, mtrr formatting should be set to 0x%013lx000, to get them aligned with
nowadays memory amounts and similar to e820 map, 16 hex digits...

> > Anyways, can I trust what dmidecode says ? I installed the ram as the board
> > manual said in banks 1A+1B (not 2A+2B) for each processor, but this program
> > says this:
> >
> > BANK0 64Mb BANK4 64Mb
> > BANK1 64Mb BANK5 64Mb
> > BANK2 1024Mb BANK6 1024Mb
> > BANK3 1024Mb BANK7 1024Mb
> >
> > I would always have thought that BANK0 would be slot 1A in first processor,
> > but it looks like not...
> > And where do the 64 Mb blocks come from ?
>
> Well if you ahve 4 sticks of 1GB, then I would hope they are installed
> as a pair for each CPU so that both CPUs can have dual channel ram
> directly connected.
>

That's how they are plugged. The strange thing is that I filled the 1st
and 2nd slot (by mobo manual numbering), but dmidecode (BIOS?) thinks they
are 3rd and 4th. I don't know if it matters, probably not, but who knows...
This s***t of PC architecture is a Pandora's Box.

> I have no idea where the 64Mb comes from.
>

Nor I do...

--
J.A. Magallon <jamagallon()ono!com> \ Software is like sex:
\ It's better when it's free
Mandriva Linux release 2008.1 (Cooker) for i586
Linux 2.6.23-jam01 (gcc 4.2.2 20070909 (4.2.2-0.RC.1mdv2008.0)) SMP PREEMPT
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
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