Why the psrinfo command shows twice as many CPUs in my Intel based Sun Fire[TM] platforms than are physically installed.

Asset ID:	1-71-1012272.1
Update Date:	2016-09-01
Keywords:

Solution Type Technical Instruction Sure

Solution 1012272.1 : Why the psrinfo command shows twice as many CPUs in my Intel based Sun Fire[TM] platforms than are physically installed.

Applies to:

Sun Fire X4170 Server - Version Not Applicable and later
Sun Fire X4170 M2 Server - Version Not Applicable and later
Sun Fire X4270 Server - Version Not Applicable and later
Sun Netra X4270 Server - Version Not Applicable and later
Sun Fire X4270 M2 Server - Version Not Applicable and later
All Platforms
***Checked for relevance on 16-Jun-2014***

Goal

Intel based Oracle Sun Fire[TM] platforms contain multiple physical processors. Running the psrinfo(1M) command however appears to show details of more physical processors than you actually have installed. This document explains why this occurs.

Solution

Starting with the V60x and V65x servers, these platforms support the Intel Xeon[TM] processor which can utilize "Hyper-Threading" technology. This allows the processor to execute two threads in parallel on one single core when the processor core is idle making multi-threaded operations run faster. (The second thread is prepared for execution once the first is complete or waiting for data) However, the operating system can appear to show more than one physical processor per true processing core, which can be confusing.

On most platforms, Hyper-Threading can be enabled/disabled in the BIOS. To control this functionality, press the <F2> key at power up to enter the BIOS setup menu. In the "Main" menu use the down arrow to highlight "Processor Settings" and press <RETURN>. On the processor screen you will see a line for "Hyper-Threading Technology" and it will show the server's current setting (enabled/disabled). If you want to change its value arrow down to this line and press return.

Due to different platform BIOS revisions and designs, the menu option for enable/disable Hyper-Threading may appear in a different location.

Here is an example of the output of "psrinfo -v" on a two processor V60x server when "Hyper-Threading" is enabled:

(note- this example is from a system running Solaris[TM] 9 8/03)
# psrinfo -v
 
Status of processor 0 as of: 04/12/2004 15:14:41
Processor has been on-line since 04/09/2004 13:46:50.
The i386 processor operates at 3190 MHz,
and has an i387 compatible floating point processor.
Status of processor 1 as of: 04/12/2004 15:14:41
Processor has been on-line since 04/09/2004 13:46:51.
The i386 processor operates at 3190 MHz,
and has an i387 compatible floating point processor.
Status of processor 2 as of: 04/12/2004 15:14:41
Processor has been on-line since 04/09/2004 13:46:53.
The i386 processor operates at 3190 MHz,
and has an i387 compatible floating point processor.
Status of processor 3 as of: 04/12/2004 15:14:41
Processor has been on-line since 04/09/2004 13:46:55.
The i386 processor operates at 3190 MHz,
and has an i387 compatible floating point processor.

Previously Published As 75457

Attachments

This solution has no attachment