If you have a single processor machine, you should not configure more than one CPU VP. ( NUMCPUVPS = 1 and SINGLE_CPU_VP = 1 ). The remainder of this section is only relevant for machines with more than one processor.

If you have a two processor machine, the standard recommendation is also to use only one CPU VP, particularly if you must run an R/3 instance on the database server. If the machine is, however, dedicated to the database, you may want to experiment by setting NUMCPUVPS to 2.

There is no hard and fast rule for NUMCPUVPS for multiprocessor machines. You should normally leave some CPU for UNIX and other tasks. One rule of thumb is to set NUMCPUVPS to the number of physical CPUs minus 1. You can get an idea of your CPU load by running onstat -g glo , waiting one minute, then running it again, and subtracting the total CPU columns for your CPU VPs to see how much CPU they used in the period. If they are all nearly 100% busy, you might benefit by adding a further CPU VP (without going over the number of physical CPUs). Instead of running onstat -g glo , you can choose Tools ® CCMS ® Control/Monitoring ® Performance Menu ® Database ® Activity ® Detail Analysis Menu ® Virtual Processor.

MULTIPROCESSOR, NUMCPUVPS & SINGLE_CPU_VP (Informix)

OSS note 41360