Abstract: A method, apparatus, system, and signal-bearing medium that, in an embodiment, select a command to send to memory. In an embodiment, the oldest command in a write queue that does not collide with a conflict queue is sent to memory and added to the conflict queue if some or all of the following are true: all of the commands in the read queue collide with the conflict queue, any read command incoming from the processor does not collide with the write queue, the number of commands in the write queue is greater than a first threshold, and all commands in the conflict queue have been present for less than a second threshold. In an embodiment, a command does not collide with a queue if the command does not access the same cache line in memory as the commands in the queue. In this way, in an embodiment, write commands are sent to the memory at a time that reduces the impact on the performance of read commands.

Abstract: Methods and systems for re-ordering commands to access memory are disclosed. Embodiments may receive a first command to access a memory bank of the memory and determine a penalty associated with the first command based upon a conflict with an access to the memory bank. The penalty, in many embodiments, may be calculated so the penalty expires when the memory bank and a data bus associated with the memory bank are available to process the first command. Then, the first command is queued and dispatched to an available sequencer after the penalty expires. After the first command is serviced, unexpired penalties of subsequent commands may be updated to reflect a conflict with the first command. Further embodiments select a command to dispatch from the commands with expired penalties, based upon priorities associated with the commands such as the order in which the commands were received and the command types.