Memory controller with separate transaction table for real time transactions

A method comprising

• receiving, at a memory controller, a plurality of memory requests from corresponding ones of a plurality of agents, wherein the plurality of memory requests includes at least one real-time memory request and at least one non-real-time memory request;
• storing the non-real-time memory requests in a non-real-time transaction table;
• storing the real-time memory requests, in a real-time transaction table, separately from the non-real-time memory requests;
• storing, in one or more additional transaction tables, memory requests initiated by one or more processing circuits;
• arbitrating among the plurality of memory requests stored in the real-time and non-real-time transaction tables, wherein arbitrating includes enforcing a quality of service policy for the real-time memory requests, wherein the arbitrating comprises:
• sharing a first pool of credits between the non-real-time transaction table, the one or more additional transaction tables;
• providing a second, separate pool of credits for the real-time transaction table;
• and
• performing a credit-based arbitration among the real-time transaction table, the non-real time transaction table, the one or more additional transaction tables;
• selecting, based on the arbitrating, one of the plurality of memory requests for further processing;
• and
• executing, by the memory controller, the one of the plurality of memory requests in a memory pipeline.

A system comprising:

• a plurality of agents configured to generate memory access requests, wherein the memory access requests include real-time requests and non-real-time requests;
• a memory subsystem including a memory and a memory controller configured to receive the memory access requests from ones of the plurality of agents, wherein the memory controller includes:
• a non-real-time transaction table configured to store incoming non-real-time requests received from ones of the plurality of agents;
• a non-real-time selection circuit configured to select ones of the non-real-time requests from the non-real-time transaction table;
• a real-time transaction table configured to store, separately from the non-real-time requests, incoming real-time requests;
• and
• a real-time selection circuit configured to select ones of the real-time requests from the real-time transaction table;
• a processor transaction table configured to store incoming memory access requests received from one or more processors;
• a graphics transaction table configured to store incoming memory access requests received from one or more graphics processing units;
• and
• an arbitration circuit configured to select a memory request from among memory access requests stored in the real-time and non-real-time transaction tables, the processor transaction table, and the graphics transaction table, wherein the arbitration circuit is configured to perform a credit-based arbitration, and wherein the non-real-time transaction table, the processor transaction table, and the graphics transaction table share a first pool of credits, and wherein a second pool of credits is reserved exclusively to the real-time transaction table;
• wherein the memory controller is configured to, in response to the arbitration circuit selecting a particular memory access request, execute the particular memory access request in the memory subsystem.