LinuxLists.cc - Opteron box and 4Gb memory

2007-10-25 21:46:16

Subject: Opteron box and 4Gb memory

Hi...

I have some Quad-Opteron boxes with 4Gb memory and two of them are
running two different Linux distros.

Box one sees 4Gb of memory, but box two just sees 3.
Their mtrr setups are different:

one:
[ 0.000000] Linux version 2.6.20...
...
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
[ 0.000000] BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 00000000b7fd0000 (usable)
[ 0.000000] BIOS-e820: 00000000b7fd0000 - 00000000b7fde000 (ACPI data)
[ 0.000000] BIOS-e820: 00000000b7fde000 - 00000000b8000000 (ACPI NVS)
[ 0.000000] BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
[ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[ 0.000000] BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
[ 0.000000] BIOS-e820: 0000000100000000 - 0000000145000000 (usable)
[ 0.000000] Entering add_active_range(0, 0, 159) 0 entries of 3200 used
[ 0.000000] Entering add_active_range(0, 256, 753616) 1 entries of 3200 used
[ 0.000000] Entering add_active_range(0, 1048576, 1331200) 2 entries of 3200
used
[ 0.000000] end_pfn_map = 1331200

cat /proc/mtrr:
reg00: base=0x00000000 ( 0MB), size=4096MB: write-back, count=1
reg01: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
reg02: base=0x140000000 (5120MB), size= 64MB: write-back, count=1
reg03: base=0x144000000 (5184MB), size= 16MB: write-back, count=1
reg04: base=0xb8000000 (2944MB), size= 128MB: uncachable, count=1
reg05: base=0xc0000000 (3072MB), size=1024MB: uncachable, count=1

two:
Linux version 2.6.22.9...
...
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e6000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 00000000b8fd0000 (usable)
BIOS-e820: 00000000b8fd0000 - 00000000b8fde000 (ACPI data)
BIOS-e820: 00000000b8fde000 - 00000000b9000000 (ACPI NVS)
BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
Entering add_active_range(0, 0, 159) 0 entries of 3200 used
Entering add_active_range(0, 256, 757712) 1 entries of 3200 used
end_pfn_map = 1048576

cicely:~# cat /proc/mtrr
reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
reg02: base=0xa0000000 (2560MB), size= 256MB: write-back, count=1
reg03: base=0xb0000000 (2816MB), size= 128MB: write-back, count=1
reg04: base=0xb8000000 (2944MB), size= 16MB: write-back, count=1

Why ? Is it a bios setup problem ? A kernel problem ?
grep HIGHMEN in configs for both kernels does not give anything, so
I still understand less this thing...

--
J.A. Magallon <magallon()unizar!es> \ Software is like sex:
\ It's better when it's free
MacOS X 10.4.8 Tiger - Darwin Kernel Version 8.8.0 PPC

2007-10-25 21:58:29

by H. Peter Anvin

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

J.A. Magallon wrote:
> Hi...
>
> I have some Quad-Opteron boxes with 4Gb memory and two of them are
> running two different Linux distros.
>
> Box one sees 4Gb of memory, but box two just sees 3.
> Their mtrr setups are different:
>
> Why ? Is it a bios setup problem ? A kernel problem ?
> grep HIGHMEN in configs for both kernels does not give anything, so
> I still understand less this thing...
>

It would depend on how the BIOS programmed the memory controllers. For
32-bit (and lots of device) compatibility, a memory hole is required
below 4 GB. Not all memory controllers can remap memory in the 3-4 GB
range above the 4 GB memory; I'm not sure if that varies with the
different Opteron processors.

Also, if you run a 32-bit distribution, you need to have HIGHMEM_64G
enabled in the kernel.

-hpa

2007-10-25 22:29:30

by Rafael J. Wysocki

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Thursday, 25 October 2007 23:58, H. Peter Anvin wrote:
> J.A. Magallon wrote:
> > Hi...
> >
> > I have some Quad-Opteron boxes with 4Gb memory and two of them are
> > running two different Linux distros.
> >
> > Box one sees 4Gb of memory, but box two just sees 3.
> > Their mtrr setups are different:
> >
> > Why ? Is it a bios setup problem ? A kernel problem ?
> > grep HIGHMEN in configs for both kernels does not give anything, so
> > I still understand less this thing...
> >
>
> It would depend on how the BIOS programmed the memory controllers. For
> 32-bit (and lots of device) compatibility, a memory hole is required
> below 4 GB. Not all memory controllers can remap memory in the 3-4 GB
> range above the 4 GB memory; I'm not sure if that varies with the
> different Opteron processors.

It shouldn't, AFAICS.

Greetings,
Rafael

2007-10-25 22:44:55

by J.A. Magallón

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

2007-10-26 08:39:18

by Arne Georg Gleditsch

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

"J.A. Magall?n" <[email protected]> writes:
> Software Memory Hole
> When "Enabled", allows software memory remapping around the memory
> hole. Options are Enabled and Disabled.
>
> Hardware Memory Hole
> When "Enabled", allows software memory remapping around the memory
> hole. Options are Enabled and Disabled. Note: this is only supported by
> Rev E0 processors and above.
> ( I have two Opteron 275 processors, no idea about revision)

The configuration register used to to reclaim DRAM lost to an MMIO
hole was introduced with revision E of the gen1 Opterons. (This
feature is supposed to work both in interleaved and non-interleaved
mode.) What does /proc/cpuinfo say? (On both?)

(Still, even without this your BIOS should be able to map your memory
so that you are able to use all 4G. Provided you disable
interleaving, I can't see that there's anything stopping the BIOS from
mapping the memory from node 1 to 0-2G and the memory from node 2 to
4-6G, leaving a 2G hole for MMIO and other junk. Whether your BIOS
actually supports this is another matter.)

--
Arne.

2007-11-04 23:19:12

by J.A. Magallón

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Thu, 25 Oct 2007 14:58:10 -0700, "H. Peter Anvin" <[email protected]> wrote:

> J.A. Magallon wrote:
> > Hi...
> >
> > I have some Quad-Opteron boxes with 4Gb memory and two of them are
> > running two different Linux distros.
> >
> > Box one sees 4Gb of memory, but box two just sees 3.
> > Their mtrr setups are different:
> >
> > Why ? Is it a bios setup problem ? A kernel problem ?
> > grep HIGHMEN in configs for both kernels does not give anything, so
> > I still understand less this thing...
> >
>
> It would depend on how the BIOS programmed the memory controllers. For
> 32-bit (and lots of device) compatibility, a memory hole is required
> below 4 GB. Not all memory controllers can remap memory in the 3-4 GB
> range above the 4 GB memory; I'm not sure if that varies with the
> different Opteron processors.
>

Well, I was able to get about 3 Gb with MTRR=discrete in the BIOS,
but I'm still in the process to find the 'software hole' option to get
the rest of the 4Gb...

But now another (perhaps related) question has arised...
I like all those 5-line progams to test system performance...;).
I just wrote a simple program that sums/muls int/float vectors with
scalar/sse operations. And my opteron box looks terribly slow.

This is my MacPro, Xeon 5130:

belly:~/bn> bn
proc: 4 x MacPro1,1 @ 2000 MHz
ram: 2048 Mb
os: unx, Darwin, 9.0.0
cc: gcc-4.0.1
vector size : 8 x 1024 x 1024
allocation: 0.01 ms
int scl add: .......... 36.78 ms, 228.07 Mips | 114.03 Mips /GHz
int scl mul: .......... 34.30 ms, 244.60 Mips | 122.30 Mips /GHz
flt scl add: .......... 34.28 ms, 244.73 Mflops | 122.37 Mflops/GHz
flt vec add: .......... 7.89 ms, 1063.15 Mflops | 531.58 Mflops/GHz
flt scl mul: .......... 34.20 ms, 245.28 Mflops | 122.64 Mflops/GHz
flt vec mul: .......... 7.90 ms, 1061.77 Mflops | 530.89 Mflops/GHz
total: 3322.19 ms

This is a normal (I think) opteron box (Opteron 846):

selene:~/bn> g
proc: 4 x x86_64 @ 2004 MHz
ram: 3496 Mb
os: unx, Linux, 2.6.9-42.0.10.ELsmp
cc: gcc-4.0.2
vector size : 8 x 1024 x 1024
allocation: 0.05 ms
int scl add: .......... 45.98 ms, 182.42 Mips | 91.03 Mips /GHz
int scl mul: .......... 44.31 ms, 189.30 Mips | 94.46 Mips /GHz
flt scl add: .......... 44.52 ms, 188.41 Mflops | 94.02 Mflops/GHz
flt vec add: .......... 10.03 ms, 836.70 Mflops | 417.52 Mflops/GHz
flt scl mul: .......... 43.32 ms, 193.63 Mflops | 96.62 Mflops/GHz
flt vec mul: .......... 10.02 ms, 836.98 Mflops | 417.65 Mflops/GHz
total: 4705.07 ms

And this is my opteron (Opteron 275)

cicely:~/bn> g
proc: 4 x x86_64 @ 2200 MHz
ram: 2914 Mb
os: unx, Linux, 2.6.23.1-desktop-1mdv
cc: gcc-4.0.2
vector size : 8 x 1024 x 1024
allocation: 0.03 ms
int scl add: .......... 87.67 ms, 95.68 Mips | 43.49 Mips /GHz
int scl mul: .......... 85.48 ms, 98.13 Mips | 44.61 Mips /GHz
flt scl add: .......... 85.90 ms, 97.66 Mflops | 44.39 Mflops/GHz
flt vec add: .......... 19.51 ms, 429.96 Mflops | 195.44 Mflops/GHz
flt scl mul: .......... 85.86 ms, 97.70 Mflops | 44.41 Mflops/GHz
flt vec mul: .......... 19.50 ms, 430.11 Mflops | 195.50 Mflops/GHz
total: 6334.96 ms

As I read in AMD site, the only difference that matters in models is
the xx5 vx xx6, related to fequency, but the processors should be just
the same.

As this only does intensive memory/fp operations, I'm not going to blame
gcc nor kernel versions here (I have compared gcc 3.4, 4.0, 4.1, and 4.2
on one of the boxes and results are very similar, the code is really
stupid and not very suitable for compiler smartness...).
I suspect it is a memory problem. It can be hardware or caused by
incorrect BIOS/kernel-mtrr setup:

selene:~> cat /proc/mtrr
reg00: base=0x00000000 ( 0MB), size=16384MB: write-back, count=1
reg01: base=0xf0000000 (3840MB), size= 256MB: uncachable, count=1

cicely:~> cat /proc/mtrr
reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
reg02: base=0xa0000000 (2560MB), size= 256MB: write-back, count=1
reg03: base=0xb0000000 (2816MB), size= 128MB: write-back, count=1
reg04: base=0xb8000000 (2944MB), size= 16MB: write-back, count=1

Any idea on what can be going on here ? I have asked the 'good opteron'
admin info about the mobo an memory of the box.

Any help will be _very_ appreciated.

TIA

--
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

2007-11-05 18:10:55

by Lennart Sorensen

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Mon, Nov 05, 2007 at 12:18:47AM +0100, J.A. Magall?n wrote:
> Well, I was able to get about 3 Gb with MTRR=discrete in the BIOS,
> but I'm still in the process to find the 'software hole' option to get
> the rest of the 4Gb...
>
> But now another (perhaps related) question has arised...
> I like all those 5-line progams to test system performance...;).
> I just wrote a simple program that sums/muls int/float vectors with
> scalar/sse operations. And my opteron box looks terribly slow.
>
> This is my MacPro, Xeon 5130:
>
> belly:~/bn> bn
> proc: 4 x MacPro1,1 @ 2000 MHz
> ram: 2048 Mb
> os: unx, Darwin, 9.0.0
> cc: gcc-4.0.1
> vector size : 8 x 1024 x 1024
> allocation: 0.01 ms
> int scl add: .......... 36.78 ms, 228.07 Mips | 114.03 Mips /GHz
> int scl mul: .......... 34.30 ms, 244.60 Mips | 122.30 Mips /GHz
> flt scl add: .......... 34.28 ms, 244.73 Mflops | 122.37 Mflops/GHz
> flt vec add: .......... 7.89 ms, 1063.15 Mflops | 531.58 Mflops/GHz
> flt scl mul: .......... 34.20 ms, 245.28 Mflops | 122.64 Mflops/GHz
> flt vec mul: .......... 7.90 ms, 1061.77 Mflops | 530.89 Mflops/GHz
> total: 3322.19 ms
>
> This is a normal (I think) opteron box (Opteron 846):
>
> selene:~/bn> g
> proc: 4 x x86_64 @ 2004 MHz
> ram: 3496 Mb
> os: unx, Linux, 2.6.9-42.0.10.ELsmp
> cc: gcc-4.0.2
> vector size : 8 x 1024 x 1024
> allocation: 0.05 ms
> int scl add: .......... 45.98 ms, 182.42 Mips | 91.03 Mips /GHz
> int scl mul: .......... 44.31 ms, 189.30 Mips | 94.46 Mips /GHz
> flt scl add: .......... 44.52 ms, 188.41 Mflops | 94.02 Mflops/GHz
> flt vec add: .......... 10.03 ms, 836.70 Mflops | 417.52 Mflops/GHz
> flt scl mul: .......... 43.32 ms, 193.63 Mflops | 96.62 Mflops/GHz
> flt vec mul: .......... 10.02 ms, 836.98 Mflops | 417.65 Mflops/GHz
> total: 4705.07 ms
>
> And this is my opteron (Opteron 275)
>
> cicely:~/bn> g
> proc: 4 x x86_64 @ 2200 MHz
> ram: 2914 Mb
> os: unx, Linux, 2.6.23.1-desktop-1mdv
> cc: gcc-4.0.2
> vector size : 8 x 1024 x 1024
> allocation: 0.03 ms
> int scl add: .......... 87.67 ms, 95.68 Mips | 43.49 Mips /GHz
> int scl mul: .......... 85.48 ms, 98.13 Mips | 44.61 Mips /GHz
> flt scl add: .......... 85.90 ms, 97.66 Mflops | 44.39 Mflops/GHz
> flt vec add: .......... 19.51 ms, 429.96 Mflops | 195.44 Mflops/GHz
> flt scl mul: .......... 85.86 ms, 97.70 Mflops | 44.41 Mflops/GHz
> flt vec mul: .......... 19.50 ms, 430.11 Mflops | 195.50 Mflops/GHz
> total: 6334.96 ms
>
> As I read in AMD site, the only difference that matters in models is
> the xx5 vx xx6, related to fequency, but the processors should be just
> the same.
>
> As this only does intensive memory/fp operations, I'm not going to blame
> gcc nor kernel versions here (I have compared gcc 3.4, 4.0, 4.1, and 4.2
> on one of the boxes and results are very similar, the code is really
> stupid and not very suitable for compiler smartness...).
> I suspect it is a memory problem. It can be hardware or caused by
> incorrect BIOS/kernel-mtrr setup:
>
> selene:~> cat /proc/mtrr
> reg00: base=0x00000000 ( 0MB), size=16384MB: write-back, count=1
> reg01: base=0xf0000000 (3840MB), size= 256MB: uncachable, count=1
>
> cicely:~> cat /proc/mtrr
> reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
> reg01: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
> reg02: base=0xa0000000 (2560MB), size= 256MB: write-back, count=1
> reg03: base=0xb0000000 (2816MB), size= 128MB: write-back, count=1
> reg04: base=0xb8000000 (2944MB), size= 16MB: write-back, count=1
>
>
> Any idea on what can be going on here ? I have asked the 'good opteron'
> admin info about the mobo an memory of the box.
>
> Any help will be _very_ appreciated.

Well what revisions are the two opterons? Is one running dual channel
memory while the other isn't perhaps? What speed and type is the ram on
the two opterons?

--
Len Sorensen

2007-11-05 18:45:41

by J.A. Magallón

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Mon, 5 Nov 2007 13:10:46 -0500, [email protected] (Lennart Sorensen) wrote:

> On Mon, Nov 05, 2007 at 12:18:47AM +0100, J.A. Magall?n wrote:
> > Well, I was able to get about 3 Gb with MTRR=discrete in the BIOS,
> > but I'm still in the process to find the 'software hole' option to get
> > the rest of the 4Gb...
> >
> > But now another (perhaps related) question has arised...
> > I like all those 5-line progams to test system performance...;).
> > I just wrote a simple program that sums/muls int/float vectors with
> > scalar/sse operations. And my opteron box looks terribly slow.
> >
> > This is my MacPro, Xeon 5130:
> >
> > belly:~/bn> bn
> > proc: 4 x MacPro1,1 @ 2000 MHz
> > ram: 2048 Mb
> > os: unx, Darwin, 9.0.0
> > cc: gcc-4.0.1
> > vector size : 8 x 1024 x 1024
> > allocation: 0.01 ms
> > int scl add: .......... 36.78 ms, 228.07 Mips | 114.03 Mips /GHz
> > int scl mul: .......... 34.30 ms, 244.60 Mips | 122.30 Mips /GHz
> > flt scl add: .......... 34.28 ms, 244.73 Mflops | 122.37 Mflops/GHz
> > flt vec add: .......... 7.89 ms, 1063.15 Mflops | 531.58 Mflops/GHz
> > flt scl mul: .......... 34.20 ms, 245.28 Mflops | 122.64 Mflops/GHz
> > flt vec mul: .......... 7.90 ms, 1061.77 Mflops | 530.89 Mflops/GHz
> > total: 3322.19 ms
> >
> > This is a normal (I think) opteron box (Opteron 846):
> >
> > selene:~/bn> g
> > proc: 4 x x86_64 @ 2004 MHz
> > ram: 3496 Mb
> > os: unx, Linux, 2.6.9-42.0.10.ELsmp
> > cc: gcc-4.0.2
> > vector size : 8 x 1024 x 1024
> > allocation: 0.05 ms
> > int scl add: .......... 45.98 ms, 182.42 Mips | 91.03 Mips /GHz
> > int scl mul: .......... 44.31 ms, 189.30 Mips | 94.46 Mips /GHz
> > flt scl add: .......... 44.52 ms, 188.41 Mflops | 94.02 Mflops/GHz
> > flt vec add: .......... 10.03 ms, 836.70 Mflops | 417.52 Mflops/GHz
> > flt scl mul: .......... 43.32 ms, 193.63 Mflops | 96.62 Mflops/GHz
> > flt vec mul: .......... 10.02 ms, 836.98 Mflops | 417.65 Mflops/GHz
> > total: 4705.07 ms
> >
> > And this is my opteron (Opteron 275)
> >
> > cicely:~/bn> g
> > proc: 4 x x86_64 @ 2200 MHz
> > ram: 2914 Mb
> > os: unx, Linux, 2.6.23.1-desktop-1mdv
> > cc: gcc-4.0.2
> > vector size : 8 x 1024 x 1024
> > allocation: 0.03 ms
> > int scl add: .......... 87.67 ms, 95.68 Mips | 43.49 Mips /GHz
> > int scl mul: .......... 85.48 ms, 98.13 Mips | 44.61 Mips /GHz
> > flt scl add: .......... 85.90 ms, 97.66 Mflops | 44.39 Mflops/GHz
> > flt vec add: .......... 19.51 ms, 429.96 Mflops | 195.44 Mflops/GHz
> > flt scl mul: .......... 85.86 ms, 97.70 Mflops | 44.41 Mflops/GHz
> > flt vec mul: .......... 19.50 ms, 430.11 Mflops | 195.50 Mflops/GHz
> > total: 6334.96 ms
> >
> > As I read in AMD site, the only difference that matters in models is
> > the xx5 vx xx6, related to fequency, but the processors should be just
> > the same.
> >
> > As this only does intensive memory/fp operations, I'm not going to blame
> > gcc nor kernel versions here (I have compared gcc 3.4, 4.0, 4.1, and 4.2
> > on one of the boxes and results are very similar, the code is really
> > stupid and not very suitable for compiler smartness...).
> > I suspect it is a memory problem. It can be hardware or caused by
> > incorrect BIOS/kernel-mtrr setup:
> >
> > selene:~> cat /proc/mtrr
> > reg00: base=0x00000000 ( 0MB), size=16384MB: write-back, count=1
> > reg01: base=0xf0000000 (3840MB), size= 256MB: uncachable, count=1
> >
> > cicely:~> cat /proc/mtrr
> > reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
> > reg01: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
> > reg02: base=0xa0000000 (2560MB), size= 256MB: write-back, count=1
> > reg03: base=0xb0000000 (2816MB), size= 128MB: write-back, count=1
> > reg04: base=0xb8000000 (2944MB), size= 16MB: write-back, count=1
> >
> >
> > Any idea on what can be going on here ? I have asked the 'good opteron'
> > admin info about the mobo an memory of the box.
> >
> > Any help will be _very_ appreciated.
>
> Well what revisions are the two opterons? Is one running dual channel
> memory while the other isn't perhaps? What speed and type is the ram on
> the two opterons?
>

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.

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 ?

Really strange...

--
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

2007-11-05 18:50:48

by Lennart Sorensen

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

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?

> 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.

I have no idea where the 64Mb comes from.

--
Len Sorensen

2007-11-05 23:03:39

by J.A. Magallón

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Mon, 5 Nov 2007 13:50:40 -0500, [email protected] (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

2007-11-08 18:08:38

by Lennart Sorensen

[permalink] [raw]

Subject: Re: Opteron box and 4Gb memory

On Tue, Nov 06, 2007 at 12:03:19AM +0100, J.A. Magall?n wrote:
> (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 ?

Seems odd if they can't just map memory as:
2GB at 0
512MB at 2GB
1GB at 4GB
512MB at 5GB

Or for that matter:
2GB at 0
2GB at 4GB
Why can't they do things as simple as that? If you have a 64bit OS that
would be perfectly fine.

It appears they have
2GB at 0
512MB at 2GB
1GB at 4GB
64MB at 5GB
32MB at 5GB+64MB
16MB at 5GB+64MB+32MB

Where did they map the rest of the ram? All I can think there is that
they messed up. Of course some think that having as much ram for XP
32bit as possible is more important than sane systems, so they will map
more in the first 4GB where XP32 can use it, and then due to alignments
and rounding of the mapping they can't get all the remaining ram mapped
above 4GB.

--
Len Sorensen