Area-optimized row hammer mitigation

A method performed by an apparatus configured to mitigate a row hammer event, comprising a content-addressable memory (CAM) and a memory media device, the method comprising:

• determining whether a row identifier of a row access request is present in a plurality of counters stored in the CAM, wherein each counter of a plurality of counters comprises a row identifier and a count, and a total number of counters in the plurality of counters is less than a total number of rows monitorable in the memory media device;
• determining whether a row identifier of a row access request is stored in the CAM;
• when the determining determines that the row identifier is stored in the CAM, updating the count of a counter corresponding to the row identifier in the plurality of counters, and if the count exceeds a predetermined threshold, triggering a response to an error in the memory media device;
• when the determining determines that the row identifier is not stored in the CAM, updating a counter of the plurality of counters to include the row identifier;
• wherein updating the counter of the plurality of counters to include the row identifier comprises:
• identifying a minimum count in the CAM among all rows of the CAM excluding rows in which a sticky bit is set;
• inserting the row identifier in the CAM in a row that corresponds to the identified minimum count;
• and
• incrementing the count in the row that corresponds to the identified minimum count.

A memory controller comprising:

• a first interface to a host system;
• a second interface coupled to a memory media device, wherein the second interface comprises a plurality of physical interfaces to the memory media device and each of the physical interfaces corresponds to a respective channel having a plurality of banks;
• at least one memory error detector comprising:
• a content addressable memory (CAM) storing a plurality of counters, each counter comprising a row identifier and a count, and a total number of counters stored in the CAM is less than a total number of rows monitorable in the memory media device;
• and
• circuitry configured to perform operations to mitigate a row hammer event, comprising:
• determining whether a row identifier of a row access request is stored in the CAM;
• when the determining determines that the row identifier is stored in the CAM, updating the count of a counter corresponding to the row identifier in the plurality of counters, and if the count exceeds a predetermined threshold, triggering a response to an error in the memory media device;
• when the determining determines that the row identifier is not stored in the CAM, updating a counter of the plurality of counters to include the row identifier;
• wherein updating the counter of the plurality of counters to include the row identifier comprises:
• identifying a minimum count in the CAM among all rows of the CAM excluding rows in which a sticky bit is set;
• inserting the row identifier in the CAM in a row that corresponds to the identified minimum count;
• and
• incrementing the count in the row that corresponds to the identified minimum count.