Memory reorder queue biasing preceding high latency operations

1. A method of operating a memory system, the method comprising:

a memory controller tracking a time remaining before a scheduled time for initiating a high priority, high latency operation to a first memory rank of the memory system, wherein a plurality of memory ranks are individually accessible by different memory access operations scheduled from a command re-order queue of the memory controller, wherein the scheduled time of the high priority, high latency operation is a future time, and wherein the command re-order queue contains memory access operations targeting the plurality of memory ranks;

in response to the time remaining reaching a pre-established early notification time before the schedule time for initiating the high priority, high latency operation:

biasing the re-order queue to prioritize scheduling of any first memory access operations that target the first memory rank; and

scheduling the first memory access operations to the first memory rank for early completion relative to other memory access operations in the command re-order queue that target other memory ranks of the plurality of memory ranks, wherein the scheduling of the first memory access operations to the first memory rank for early completion causes the first memory access operations to be completed before performing the high priority, high latency operation at the first memory rank; and

performing the high priority, high latency operation at the first memory rank at the scheduled time;

wherein the biasing of the command re-order queue and scheduling of the first memory access operations triggers a faster depletion of first memory access commands remaining within the command re-order queue before the high priority, high latency operation is performed at the first memory rank.

2. The method of claim 1 , wherein the memory controller tracking the time remaining before the scheduled time further comprises:

setting a counter to track a period between performing a previous high priority, high latency operation and the high priority, high latency operation;

performing the high priority, high latency operation when the counter expires; and

resetting the counter to track a next high priority, high latency operation, wherein a scheduled time for performing a next high priority, high latency operation is known based on one of a pre-established periodicity for performing high priority, high latency operations and an advance notification of the scheduled time to a next high priority, high latency operation.

3. The method of claim 1 , wherein the high priority, high latency operation is a high priority memory refresh operation and the memory access operations are read commands, and the method comprises:

determining a count of deferred memory refresh operations for the first memory rank;

in response to the count approaching a high priority threshold, issuing an early high priority refresh notification for the first memory rank, wherein the high priority threshold indicates the scheduled time for performing a memory refresh operation as a high priority memory refresh operation at the first memory rank;

in response to issuance of the early high priority refresh notification, modifying a read re- order queue to give priority scheduling to at least one read command targeting the first memory rank; and

executing one or more of the at least one read command on the first memory rank according to the priority scheduling.

4. The method of claim 3 , further comprising:

in response to the count being equal to the high priority threshold, refreshing the first memory rank.

5. The method of claim 4 , further comprising preventing at least one new read command that is targeting the first memory rank from entering the read re-order queue following receipt of the early high priority refresh notification and until performance of the high priority refresh operation reaches a pre-determined completion point.

6. The method of claim 3 , further comprising deferring a memory refresh operation to the first memory rank in response to the count not being equal to the high priority threshold.

7. The method of claim 3 , further comprising;

in response to the read re-order queue not having any remaining read commands that target the first memory rank prior to the count being equal to the high priority threshold, refreshing the first memory rank prior to the scheduled time; and

resetting the count to an initial state and begin tracking a next count for a next high priority memory refresh operation.