US Patent 9299400 Distributed row hammer tracking

A memory controller issues a targeted refresh command in response to detection by a distributed detector. A memory device includes detection logic that monitors for a row hammer event, which is a threshold number of accesses to a row within a time threshold that can cause data corruption to a physically adjacent row (a “victim” row). The memory device sends an indication of the row hammer event to the memory controller. In response to the row hammer event indication, the memory controller sends one or more commands to the memory device to cause the memory device to perform a targeted refresh that will refresh the victim row.