rdisp/scheduler/timeslice_millis is a SAP Parameter attribute which is used to control Timeslice for the kernel scheduler (in ms) information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
The kernel scheduler periodically compares the priority of the requests
currently running in a dialog work process with those in waiting in a
queue for a free dialog work process. If necessary, a request with a
lower priority is rolled out of a dialog work process so that a waiting
request with higher priority can be processed.
This parameter defines the time interval (in milliseconds) for the
periodic check. A time interval of 0 completely deactivates the check
(and therefore scheduling by priorities).
If you set too low a value, this can have a negative effect on
performance, since the priority check is performed too often. If you set
too high a value, the kernel scheduler will be slow in reacting if a
request with higher priority requests immediate provision of a dialog
work process.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.