User guide

80 DC 900-1338I
Protocol Software Toolkit Programmer Guide
4.3.2.3 Tick and Time Slice Lengths
Ticks measure the duration of alarms and the system’s time slice period. The cf_ltick
field of the configuration table specifies the length of a tick (1 to 222 milliseconds).
The length of a tick should be set to the smallest of the following values:
• The minimum duration of any alarm in the system
• The maximum acceptable error in an alarm duration
• The desired time slice duration
Because each tick corresponds to a clock interrupt and involves processing by the clock
interrupt service routine, setting the tick length to a smaller value than is actually
required results in increased overhead and a degradation in system performance.
The
cf_lslice field of the configuration table specifies the number of ticks for each time
slice. The time slice should be long enough to allow each task adequate processing time
before being preempted (in other words, to avoid “thrashing”), but not so long that any
task is able to prevent other tasks from executing in a timely fashion. (If no tasks in the
system are created with time slicing enabled, the length of the time slice is immaterial.)