In an example, there is disclosed a computing apparatus, having: a first master having a first ordinal quality of service (QoS) profile; a second master having a second ordinal QoS profile, wherein the second ordinal QoS profile is higher in order than the first ordinal QoS profile; a slave; a multiplexed interconnect to communicatively couple the first master and second master to the slave with a priority according to the ordinal QoS profiles; and one or more logic elements, including at least one hardware logic element, providing a QoS engine to: determine that the first master has initiated a slave operation via the interconnect; determine that completing the slave operation according to a QoS criterion provided by the second master requires elevated QoS; and promote the first master to a third ordinal QoS profile having an order higher than the second ordinal QoS profile.