Dual-Core CPU's

[Matthew Pegge_1]

How can I tell (on RHAS 3.0) whether the CPU's are single or dual core??

Thanks

[Bill Thorsteinson · Accepted solution]

I am running Debian with a multi processor
kernel, so your millage may vary.

cat /proc/cpuinfo

Dual core should have an entries for
physical id, and siblings.

I believe the listing "siblings 2" indicates
dual core.

[Vipulinux]

Hi

Do the foll:
cat /proc/cpuinfo

It will list the no. of cpu's, speed etc.

Cheers

[Alan_152]

You will also have to know if you have threading on or off to properly read this file... easy enough to figure out, though.

[Ramassh]

Is it possible to get a copy of /proc/cpuinfo from a dual core, hyperthreaded Linux system?

Thanks

[Alan_152]

[root@vader root]# cat /proc/cpuinfo
processor : 0
vendor : GenuineIntel
arch : IA-64
family : Itanium 2
model : 2
revision : 2
archrev : 0
features : branchlong
cpu number : 0
cpu regs : 4
cpu MHz : 1599.705144
itc MHz : 1599.705144
BogoMIPS : 2390.75
siblings : 1

processor : 1
vendor : GenuineIntel
arch : IA-64
family : Itanium 2
model : 2
revision : 2
archrev : 0
features : branchlong
cpu number : 0
cpu regs : 4
cpu MHz : 1599.705144
itc MHz : 1599.705144
BogoMIPS : 2390.75
siblings : 1

processor : 2
vendor : GenuineIntel
arch : IA-64
family : Itanium 2
model : 2
revision : 2
archrev : 0
features : branchlong
cpu number : 0
cpu regs : 4
cpu MHz : 1599.705144
itc MHz : 1599.705144
BogoMIPS : 2390.75
siblings : 1

processor : 3
vendor : GenuineIntel
arch : IA-64
family : Itanium 2
model : 2
revision : 2
archrev : 0
features : branchlong
cpu number : 0
cpu regs : 4
cpu MHz : 1599.705144
itc MHz : 1599.705144
BogoMIPS : 2390.75
siblings : 1

[Ramassh]

Thanks Alan - that was fast.

But I cannot see any "siblings 2", as described by Bill.

Is this a single dual-core CPU system with Hyper-threading? Or a single 4-core CPU with no Hyper-threading? How can we differentiate them?

Thanks.

[Alan_152]

Sorry... this is a dual core unit with threading turned on...

[Ramassh]

So how can I identify which threads are from the same core?

Thanks.

[Stuart Browne]

Ok, here's a single processor, P4+HT cpuinfo:

processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz
stepping : 1
cpu MHz : 3015.840
cache size : 1024 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe constant_tsc pni monitor ds_cpl cid xtpr
bogomips : 6039.01

processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz
stepping : 1
cpu MHz : 3015.840
cache size : 1024 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe constant_tsc pni monitor ds_cpl cid xtpr
bogomips : 6030.22


'siblings' is set to 2 here, whilst 'physical id' is set to 0 for both. I've not seen a 'cpuinfo' output for one of the new dual-core intel x86-based CPU's, and I'm pretty sure Itanium's don't use 'Hyper threading', so..

In any case, as can be seen from Ivan's output, there are no 'physical id's involved with Itanium systems.

(aside: HP have a 16-way Itanium-2 system running RHAS4 up on testdrive! Woo!)

[Ramassh]

Hi Stuart,

Thanks for the output. Interestingly your cpuinfo has following lines..

core id : 0
cpu cores : 1

Cheers

[Stuart Browne]

As I stated, this was from a single-core CPU, a P4 3Ghz with Hyper-Threading. This was not one of the new Intel Dual-Core CPU's.

[xin li_2]

Dual CPUs should has two different "physical id"

"siblings 2" means two logic CPUs on that physical CPU (Hyper Threading)

http://www.intel.com/cd/ids/developer/asmo-na/eng/269421.htm?page=2

[xin li_2]

Sorry, two CPUs should at least have two unique "core id".

"Physical id" is for physical package.