Memory system using host memory buffer and operation method thereof

1. An operation method of a memory system which includes a host and a storage device, the method comprising:

allocating a portion of a host memory included in the host as a host memory buffer for the storage device;

setting a set feature command to enable the host memory buffer;

setting a retention command comprising information about a response speed of the host memory buffer;

selecting an operation mode of the host memory buffer, based on the retention command; and

selecting a power state, among a plurality of power states supported by a controller of the storage device, based on a performance objective of the operation mode of the host memory buffer.

2. The method of claim 1 , further comprising:

selecting, by the host, a non-operational power state as a power state of the controller.

3. The method of claim 2 , further comprising:

receiving, at the controller, at least a portion of data present in the host memory buffer for performing an operation permitted in the non-operational power state.

4. The method of claim 3 , further comprising:

sending, by the controller, an acknowledge signal providing notification that the receiving of the at least the portion of the data present in the host memory buffer is completed, to the host, and

preventing the controller from accessing the host memory buffer after the acknowledge signal is sent.

5. The method of claim 2 , further comprising:

preventing the controller from accessing the host memory buffer, after the non-operational power state is selected.

6. The method of claim 5 , further comprising:

preventing the controller from accessing the host memory buffer based on the retention command.

7. The method of claim 1 , further comprising:

permitting the controller to access the host memory buffer based on an expected response time of the host memory buffer being smaller than a reference response time.

8. The method of claim 7 , further comprising:

based on the access of the controller to the host memory buffer being permitted, selecting, by the host, an active power state as a power state of the controller.

9. The method of claim 1 , wherein the host memory buffer comprises at least two regions, and

wherein the retention command comprises information about a response speed for each of the at least two regions.

10. The method of claim 1 , further comprising:

receiving, at the controller, a retention recovery command from the host; and

incorporating data present in the storage device in the host memory buffer.

11. An operation method of a memory system which includes a host and a storage device, the method comprising:

allocating a portion of a host memory included in the host as a host memory buffer for the storage device;

setting a set feature command to enable the host memory buffer;

setting a retention command comprising information about a response speed of the host memory buffer; and

selecting an operation mode of the host memory buffer, based on the retention command.

12. The method of claim 11 , further comprising:

receiving at least a portion of data present in the host memory buffer to be stored in the storage device.

13. The method of claim 12 , further comprising:

sending, by a controller of the storage device, an acknowledge signal providing notification that the receiving of the at least the portion of the data present in the host memory buffer is completed, to the host, and

preventing the controller from accessing the host memory buffer after the acknowledge signal is sent.

14. The method of claim 13 , further comprising:

preventing the controller from accessing the host memory buffer based on the retention command.

15. The method of claim 11 , wherein the retention command comprises an address and a retention level of the host memory buffer, and

wherein the retention level is determined by comparing an expected response speed of the host memory buffer and at least one reference response time.

16. The method of claim 15 , further comprising:

selecting, by a controller, an operation mode of the host memory buffer based on the retention level included in the retention command.

17. The method of claim 15 , wherein the host memory buffer comprises at least two regions, and

wherein the retention command comprises a retention level for each of the at least two regions.

18. The method of claim 11 , further comprising:

receiving, at a controller, a retention recovery command from the host; and

incorporating data present in the storage device in the host memory buffer.

19. A storage device which shares a host memory of a host, comprising:

an interface configured to access a partial region of the host memory as a host memory buffer of the storage device; and

a storage controller configured to:

select one of a first mode, a second mode, and a third mode as an operation mode of the host memory buffer based on a response speed of the host memory buffer, and

based on the first mode being selected, permit the host memory buffer to access the storage device,

based on the second mode being selected, permit the host memory buffer to access the storage device, and receiving and storing, by the storage device, frequently used data of data present in the host memory buffer, and

based on the third mode being selected, prevent the host memory buffer from accessing the storage device.

20. The storage device of claim 19 , wherein, while the access of the storage device to the host memory buffer is not permitted in the third mode, an enable host memory (EHM) command for an enable of the host memory buffer is in an enable state, and a memory return (MR) command for a return of the host memory buffer is in a disable state.

21. A host apparatus connected to a storage device, the host apparatus comprising:

one or more memories storing instructions; and

one or more processors configured to execute the one or more instructions to:

obtain a response speed of a host memory buffer corresponding to the storage device, the host memory buffer allocated in a portion of a host memory included in the host apparatus, as a host memory buffer for the storage device;

generate a retention command based on the response speed of the host memory buffer, the retention command comprising information about the response speed of the host memory buffer; and

select an operation mode of the host memory buffer, based on the retention command.

22. The host apparatus of claim 21 , wherein the one or more processors are further configured to select a power state, among a plurality of power states supported by a controller, based on a performance characteristics of the operation mode of the host memory buffer.