rdisp/max_sleep is a SAP Parameter attribute which is used to control Wakeup time for dispatcher 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 .
Normally the dispatcher becomes active as soon as there is a request in
its request queue, or input needs to be read from an SAP GUI or from the
message server. However, it also becomes active after the period
configured by the parameter rdisp/max_sleep to execute periodic tasks,
for example.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.