Hyper Threading on Intel Xeon

[kenny chia]

Hi
I own 2 boxes of dual Intel Xeon servers
Both have Red Hat 7.3 installed.
One is running with hyperthreading enabled (confirmed with the top command, 4 CPUs total), but the other shows only 2 CPUs in the top command

What could be wrong with the other box?

I noticed that the box which show 4 cpus have 2 CPUS with stepping number 7, while the other one has stepping 4 and stepping 7.

Below is the /proc/cpuinfo of the box that shows 4 CPU

processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 7
cpu MHz : 2800.147
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
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 tm
bogomips : 5583.66

processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 7
cpu MHz : 2800.147
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
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 tm
bogomips : 5596.77

processor : 2
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 9
cpu MHz : 2800.147
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
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 tm
bogomips : 5596.77

processor : 3
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 9
cpu MHz : 2800.147
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
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 tm
bogomips : 5596.77

[Vitaly Karasik_1]

do you use the same kernel on both servers?

[Stuart Browne]

Do you have Hyperthreading enabled in the BIOS ? I know it's configurable on the recent Proliant server range.

Also, are you using the SMP kernel on the server showing only 2 processors?

[kenny chia]

Hi
I need to set the BIOS settings.. problem solved