Low power optimization based upon host exit latency
There is a tradeoff between the amount of power consumption decreased and the latency needed to return a data storage device back to an operational power mode. When the data storage device receives a wake up indication from a host device, a controller of the data storage device initiates a counter in order to determine a host exit latency. Based on the host exit latency, the controller determines a group of low power state entrance actions from a plurality of groups to perform during a next entrance into a firmware active idle state based on an associated completion wake up time and the host exit latency. The controller selects the group whose completion wake up time is closest to the host exit latency and less than or equal to the host exit latency. The controller performs the selected groups low power state entrance actions during a next entrance into the firmware active idle state.
1. A data storage device, comprising:
a memory device; and
a controller coupled to the memory device, wherein the controller is configured to:
receive a wake up indication from a host device, wherein the data storage device is in a low power state;
receive a doorbell from the host device indicating that a new command is in a submission queue of the host device;
determine a host exit latency, wherein the host exit latency is a time between the wake up indication and the doorbell; and
utilize the host exit latency to select a group of actions from a plurality of group of actions based on the determining, wherein each of the plurality of group of actions comprises a different amount of low power state entrance actions to complete during a next low power state entrance.
2. The data storage device of claim 1 , wherein the different amount of low power state entrance actions is a configurable number of low power state entrance actions.
3. The data storage device of claim 1 , wherein at least one of the low power state entrance actions of one or more group of actions of the plurality of group of actions is the same.
4. The data storage device of claim 1 , wherein at least one of the low power state entrance actions of one or more group of actions of the plurality of group of actions is different.
5. The data storage device of claim 1 , wherein each group of the plurality of group of actions is associated with a completion wake up time, and wherein the completion wake up time corresponds to a time to restore the data storage device from a low power state to a normal operating power state.
6. The data storage device of claim 5 , wherein the controller is further configured to, when utilizing the host exit latency to select the group of actions from the plurality of group of actions, determine that there is at least one completion wake up time that is less than or equal to the host exit latency.
7. The data storage device of claim 6 , wherein the controller is further configured to select the group of actions that has the completion wake up time that is closest to the host exit latency when there is at least one completion wake up time that is less than or equal to the host exit latency.
8. The data storage device of claim 6 , wherein the controller is further configured to select the group of actions that has the completion wake up time that is closest to the host exit latency upon determining that all of the completion wake up times are greater than the host exit latency.
9. The data storage device of claim 5 , wherein the completion wake up time is dependent on the low power state entrance actions of the group of actions selected and a setup time of the data storage device.
10. The data storage device of claim 1 , wherein the controller is further configured to:
perform the low power state entrance actions of the group of actions selected upon determining that an idle time timeout threshold has been reached; and
transition the data storage device to the low power state.
11. A data storage device, comprising:
a memory device; and
a controller coupled to the memory device, wherein the controller is configured to:
determine a host exit latency, wherein the host exit latency is a time between receiving a wake up indication from a host device and receiving a doorbell subsequent to receiving the wake up indication from the host device; and
select a group of actions from a plurality of group of actions based on the determining, wherein each of the plurality of group of actions comprises a different amount of low power state entrance actions to complete during a next low power state entrance.
12. The data storage device of claim 11 , wherein the controller is further configured to:
initiate a counter responsive to receiving the wake up indication from the host device; and
stop the counter responsive to receiving the doorbell from the host device, wherein the time is determined based on the counter.
13. The data storage device of claim 11 , wherein the data storage device is in a low power state during the determining.
14. The data storage device of claim 11 , wherein a first group of actions of the plurality of group of actions comprises all of the low power state entrance actions.
15. The data storage device of claim 14 , wherein each group of actions other than the first group of actions of the plurality of group of actions comprises less than all of the low power state entrance actions.
16. The data storage device of claim 15 , wherein a number of low power state entrance actions of each group of actions other than the first group of actions is different from each other.
17. The data storage device of claim 16 , wherein the group of actions selected has a completion wake up time less than the host exit latency, and wherein the completion wake up time is calculated based on a time to complete a restoration from each of the low power state entrance actions of the group of actions.
18. The data storage device of claim 17 , wherein the completion wake up time is further calculated based on a fine-tuning parameter, and wherein the fine-tuning parameter is dependent on a setup time of the data storage device.
19. A data storage device, comprising:
means for storing data; and
a controller coupled to the means for storing data, wherein the controller is configured to:
determine that an idle time timeout threshold has been reached;
perform a number of low power state entrance actions based on a previously determined host exit latency, wherein a completion wake up time to complete a restoration from the number of low power state entrance actions is less than the previously determined host exit latency; and
transition the data storage device into a low power mode.
20. The data storage device of claim 19 , wherein the number of low power state entrance actions is dynamic.