6850 shows 16 CPUs?

[Robert Wilson]

Hi,

This weekend, I built Debian SMP with kernel 2.6.20-7 and noticed I was 
seeing 16 CPUs on our Dell 6850. Initially, it only saw 8 CPUs, kernel 
2.6.18-x. Then Monday, one of our RedHat admins built a development SMP 
system and it too reports 16 CPUs, kernel 2.6.9-42. Yet when I check the 
specifications, it looks like we should have 7130M, dual-core processors, or 
a maximum of 8 CPUs. Needless to say, I'm a little confused:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 6
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 8
cpu MHz         : 3192.477
cache size      : 8192 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 6
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht t
m pbe nx lm pni monitor ds_cpl est tm2 cid xtpr
bogomips        : 6389.12
[root at lab6850 proc]# grep processor cpuinfo
processor       : 0
processor       : 1
processor       : 2
processor       : 3
processor       : 4
processor       : 5
processor       : 6
processor       : 7
processor       : 8
processor       : 9
processor       : 10
processor       : 11
processor       : 12
processor       : 13
processor       : 14
processor       : 15

Regardless, the machines run like a bat-out-of-Redmond and we're seeing some 
impressive, GigE performance. With four, GigE streams into Intel Pro/1000 
MT, dual-port cards, it looks like we can get 70% of full bandwidth, 64B 
packets before seeing errors.

What I can't figure out is why the kernel is reporting twice the number of 
CPUs as expected.

One other 'strangeness' is the dual-port, Intel Pro/1000 MT in slot 2 seems 
to be quite happy. I installed it with the power cords pulled from the box. 
Yet curiously, the "PowerEdge Additional Information" warns against this. 
Needless to say, this is amusing . . . it shouldn't work but there it is. We 
have all four 'eth' devices although under debian and a kernel.org built 
kernel, they are listed as 'eth0, eth1, eth4, eth5', the Intel Pro/1000 MT 
cards. The Broadcom, Teragon drivers are attached to 'eth2 and eth3'. The 
RedHat 2.6.9-42 shows them as 'eth0, eth1, eth2, eth3' with the Broadcoms on 
'eth4, eth5'.

Thanks,
Bob Wilson

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