A current value of a changing operating-system-level condition can be determined, wherein the operating-system level condition is a condition of a host related to an operating system resource utilization or an operating system experienced latency. The operating-system level condition can be a condition of a layer of the OSI model above the Data Link Layer. An inbound blocking factor algorithm can execute that uses the determined current value as a variable. A value for an inbound blocking factor can be generated as a result of executing the inbound blocking factor algorithm. The generated value can be utilized as the inbound blocking factor to determine a manner in which incoming messages are to be conveyed from a network adaptor, through an adaptor interface boundary, to an operating system of the host.