Re: Opteron box and 4Gb memory
- From: lsorense@xxxxxxxxxxxxxxxxxxx (Lennart Sorensen)
- Date: Mon, 5 Nov 2007 13:10:46 -0500
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
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