Performance considerations

The Radio Timeslot API shares core peripherals with the SoftDevice, and application-requested timeslots are scheduled along with other SoftDevice activities. Therefore, the use of the Timeslot feature may influence the performance of the SoftDevice.

The configuration of the SoftDevice should be considered when using the Radio Timeslot API. A configuration which uses more radio time for native protocol operation will reduce the available time for serving timeslots and result in a higher risk of scheduling conflicts.

All Timeslot requests should use the lowest priority to minimize disturbances to other activities. At this priority level, only flash writes might be affected. The high priority should only be used when required, such as for running a radio protocol with certain timing requirements that are not met by using normal priority. By using the highest priority available to the Timeslot API, non-critical SoftDevice radio protocol traffic may be affected. The SoftDevice radio protocol has access to higher priority levels than the application. These levels will be used for important radio activity, for instance when the device is about to lose a connection.

See Scheduling for more information on how priorities work together with other modules like the Bluetooth low energy protocol stack, the Flash API etc.

Timeslots should be kept as short as possible in order to minimize the impact on the overall performance of the device. Requesting a short timeslot will make it easier for the scheduler to fit in between other scheduled activities. The timeslot may later be extended. This will not affect other sessions, as it is only possible to extend a timeslot if the extended time is unreserved.

It is important to ensure that a timeslot has completed its outstanding operations before the time it is scheduled to end (based on its starting time and requested length), otherwise the SoftDevice behavior is undefined and my result in an unrecoverable fault.