Monitoring CPU VPs (Informix) (SAP Library

Monitoring CPU VPs (Informix)

Use

You can use the SAP/Informix database monitor to monitor Informix CPU virtual processors (VPs). For up-to-date recommendations, see SAP Note 41360.

Prerequisites

You specify the number of CPU VPs with the NUMCPUVPS and SINGLE_CPU_VP parameters of the Informix ONCONFIG file.

Procedure

If you have a single processor machine

Do not configure more than one CPU VP. The settings for one CPU VP are:

NUMCPUVPS 1

SINGLE_CPU_VP 1

If you have a two processor machine

Normally use only one CPU VP, particularly if you are running an SAP instance on the database server. The correct settings are:

NUMCPUVPS 1

SINGLE_CPU_VP 1

If the machine is a standalone database system – that is, dedicated to the database – you might want to experiment by using the following settings:

NUMCPUVPS 2

SINGLE_CPU_VP 0

If you have a multiprocessor machine

There is no simple rule for the number of CPU VPs for multiprocessor machines. You should normally leave some CPU for the operating system and other tasks.

A good rule is to set NUMCPUVPS to the number of physical CPUs minus 1.

To estimate your CPU load, so that you can see if you need to add a CPU VP:

Run the Informix command onstat -g glo , wait one minute, then run it again. Subtract the total CPU columns for your CPU VPs to see how much CPU they used in the period.

Choose Tools ® CCMS ® Control/Monitoring ® Performance Menu ® Database ® Activity ® Detail Analysis Menu ® Virtual Processor.

If the CPUs are all nearly 100% busy, you might benefit by adding a further CPU VP, but do not exceed the number of physical CPUs.

For more information, see MULTIPROCESSOR, NUMCPUVPS & SINGLE_CPU_VP (Informix).

See also:

MULTIPROCESSOR (Informix)

NUMCPUVPS (Informix)

SINGLE_CPU_VP (Informix)