Determining how many CPUs you have on HP-UX

Answer

This document explains how to count the number of processors on your system as IBM Informix® products defines a processor. Various IBM Informix® products are tuned based on the number of processors on your system. The NUMCPUVPS or VPCLASS ONCONFIG configuration parameter, for example, should be set to one less than the actual number of physical CPUs present in the server.

A processor is a device that operates on core. With multiple core technology, this can be a single device or a device that has multiple core "processors". IBM Informix® products consider these multiple cores as separate physical processors.

On any HP-UX system, the ioscan command lists how many processors(single or multiple core) are on your system. The ioscan command (located in /usr/sbin) outputs a list of all IO devices. Each line in the output that begins with processor represents a processor that is either a single device or an instance of a multiple core device.

Use the following command line to include the processors in the output and automatically count them using grep (pattern match) and wc (character count). For more information see your Operating System man pages.

/usr/sbin/ioscan -kf | grep processor | wc -l

Example 1:

This example is from a machine with 2 processors.


$   /usr/sbin/ioscan -kf|grep processor|wc -l
2

Note: You would set the NUMCPUVPS or VPCLASS parameter to 1 in this example.

Example 2:

This example is from a machine with 4 processors.

$   /usr/sbin/ioscan -kf|grep processor|wc -l
4

This example is from a machine with 4 processors. The Line count (wc -l) is left off to show the actual ioscan and grep output.


$   /usr/sbin/ioscan -kf|grep processor
processor   0  120            processor  CLAIMED     PROCESSOR    Processor
processor   1  121            processor  CLAIMED     PROCESSOR    Processor
processor   2  122            processor  CLAIMED     PROCESSOR    Processor
processor   3  123            processor  CLAIMED     PROCESSOR    Processor

Note: You would set the NUMCPUVPS or VPCLASS parameter to 3 in this example.