Some Intel processors use hyperthreading, a technology that counts each physical processor as a specific number of logical processors. The operating system and any programs running on the machine see the number of logical processors, not the number of physical processors.

When a machine uses hyperthreading, Windows Task Manager lists the logical processors, not the physical ones. You specify the number of logical processors in the environment variable. When a machine uses hyperthreading, BIRT iHub calculates the number of bound processors by dividing the number of bound logical processors by the number of logical processors for each physical processor. If the result contains a decimal component, BIRT iHub uses the next highest integer. For example, it rounds 4.3 to 5. In the following example, a machine has four physical processors. With hyperthreading enabled, each physical processor corresponds to two logical processors. The machine has the following logical processors available:

If you bind BIRT iHub to the five logical processors 0, 2, 3, 6, and 7, it calculates the number of bound processors as:

BIRT iHub rounds this number up to determine that you have three bound processors.