Monday, July 19, 2010

How to know Hyperthreading is activated from CPU Information generated by dmidecode

According to Intel® Hyper-Threading Technology
"Intel® Hyper-Threading Technology (Intel® HT Technology) is available on laptop, desktop, server, and workstation systems. Look for systems with the Intel® HT Technology logo which your system vendor has verified utilize Intel® HT Technology".
As System Administrator, how do we detect the Hyperthreading in Linux Server? Which CPU are physical and which is logical? For those running HPC, this could be important as you are more interested in number of physical CPU rather than Logical CPU count.

For more information on dmidecode. See dmidecode - Finding the hardware details remotely

Well here come dmidecode to the rescue:

Physical CPU Result (Notice the Status: "Status: Populated, Enabled")
Physical CPU
Handle 0x000C, DMI type 4, 32 bytes
Processor Information
Socket Designation: Socket 1 CPU 1
Type: Central Processor
Family: Xeon
Manufacturer: GenuineIntel
ID: 43 0F 00 00 01 03 00 00
Signature: Type 0, Family 15, Model 4, Stepping 3
Flags:
FPU (Floating-point unit on-chip)
CX8 (CMPXCHG8 instruction supported)
APIC (On-chip APIC hardware supported)
Version: Intel Xeon
Voltage: 1.5 V
External Clock: 200 MHz
Max Speed: 4000 MHz
Current Speed: 3800 MHz
Status: Populated, Enabled
Upgrade: ZIF Socket
L1 Cache Handle: 0x0004
L2 Cache Handle: 0x0005
L3 Cache Handle: Not Provided

Logical CPU Result (Notice the Status: "Status: Unpopulated")
Handle 0x000D, DMI type 4, 32 bytes
Processor Information
Socket Designation: Socket 2 CPU 2
Type: Unknown
Family: Unknown
Manufacturer: Not Specified
ID: 00 00 00 00 00 00 00 00
Version: Not Specified
Voltage: 1.5 V
External Clock: 200 MHz
Max Speed: 4000 MHz
Current Speed: 3800 MHz
Status: Unpopulated
Upgrade: ZIF Socket
L1 Cache Handle: 0x0006
L2 Cache Handle: 0x0007
L3 Cache Handle: Not Provided

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