Synchronising throttled memory controllers in partitioned memory subsystem

A method for synchronising memory controllers, each controlling a partition of a partitioned memory subsystem, comprises forwarding 606 a synchronisation command to a pre-determined master memory controller, the command including information identifying (selecting) a group of controllers to be synchronised. The master controller then forwards 608 the command to each memory controller, including the master memory controller itself. Each controller then de-asserts 612 a status bit to confirm that they have receiving the command, and then each of the selected memory controllers forward 616 the command to associated power logic which powers the memory controller. The power logic then resets its timers so that the associated controllers are synchronised. This method is for throttled systems where a memory controller can only perform a certain number of commands in a predetermined time window, so that the windows of memory controllers completing the same task (where the memory channels are interleaved, for example) can be aligned with each other. Timers can be set to ensure the process is repeated if synchronisation in the same clock cycle fails.