Thread and Process Priorities

At any time, the thread running is the one with the highest priority which is ready to run. The priority of a thread is simply a number; the value determines the priority; the greater the number, the higher the priority.

This value is termed the absolute priority of the thread and is calculated from the priority values assigned through the API to both the thread and the process which owns that thread.

A process can take one of eight discrete priority values; these are the individual enumerators of the TProcessPriority enumeration, defined in e32std.h, and range from EPriorityLow, the lowest, to EPrioritySupervisor, the highest.

In practice, user processes can only be assigned priorities that are less than EPriorityWindowServer, i.e. a user process can only be assigned one of the values:

• EPriorityLow

• EPriorityBackground

• EPriorityForeGround

• EPriorityHigh

A process priority can be assigned:

• when the associated .exe is built; this is done by specifying the value in the .mmp file that defines the project.

• using RProcess::SetPriority().

Using Makmake in the Build Tools Guide.