QoS-aware scheduling

A memory controller comprising:

• an agent interface unit coupled to receive a plurality of memory operations from one or more sources, wherein each memory operation of the plurality of memory operations is accompanied by a quality of service (QoS) parameter specifying a requested quality of service for the memory operation, wherein the plurality of memory operations are classified into one of at least two traffic classes, wherein the QoS parameter definition is different for the different traffic classes;
• and
• a plurality of memory channel units, each of the plurality of memory channel units configured to interface to memory on a respective memory channel of the plurality of memory channels;
• wherein the agent interface unit is configured to identify a memory channel of the plurality of memory channels for each memory operation of the plurality of memory operations, wherein the identified memory channel is the memory channel to which the memory operation is directed, and wherein the agent interface unit is configured to independently schedule memory operations to each memory channel unit, and wherein scheduling decisions among memory operations directed to a particular memory channel are responsive, at least in part, to the QoS parameters of the memory operations, and wherein the ranking of the QoS parameters of each traffic class with respect to the QoS parameters of other traffic classes is dependent on a state of the memory controller.