topic Dual-Core CPU's in Operating System - Linux

Dual-Core CPU's

Matthew Pegge_1 — Wed, 08 Mar 2006 10:16:38 GMT

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

Thanks

Re: Dual-Core CPU's

Bill Thorsteinson — Wed, 08 Mar 2006 10:24:43 GMT

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.

Re: Dual-Core CPU's

Vipulinux — Wed, 08 Mar 2006 10:34:46 GMT

Hi

Do the foll:
cat /proc/cpuinfo

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

Cheers

Re: Dual-Core CPU's

Alan_152 — Thu, 09 Mar 2006 11:29:10 GMT

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

Re: Dual-Core CPU's

Ramassh — Thu, 06 Apr 2006 16:50:06 GMT

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

Thanks

Re: Dual-Core CPU's

Alan_152 — Thu, 06 Apr 2006 17:35:19 GMT

[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

Re: Dual-Core CPU's

Ramassh — Thu, 06 Apr 2006 17:50:26 GMT

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.

Re: Dual-Core CPU's

Alan_152 — Thu, 06 Apr 2006 17:52:25 GMT

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

Re: Dual-Core CPU's

Ramassh — Thu, 06 Apr 2006 17:56:26 GMT

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

Thanks.

Re: Dual-Core CPU's

Stuart Browne — Thu, 06 Apr 2006 18:19:52 GMT

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!)

Re: Dual-Core CPU's

Ramassh — Thu, 06 Apr 2006 19:22:53 GMT

Hi Stuart,

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

core id : 0
cpu cores : 1

Cheers

Re: Dual-Core CPU's

Stuart Browne — Fri, 07 Apr 2006 00:51:09 GMT

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.

Re: Dual-Core CPU's

xin li_2 — Thu, 29 Jun 2006 17:01:07 GMT

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

Re: Dual-Core CPU's

xin li_2 — Mon, 03 Jul 2006 19:31:55 GMT

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

"Physical id" is for physical package.