Operating method of host device and storage device using credit

1. An electronic device comprising a host device connected to a storage device, wherein the host device comprises:

processing circuitry configured to

process a submission queue (SQ) and a completion queue (CQ), wherein the SQ is a processing standby line of a command, and the CQ is a processing standby line of a response received from the storage device;

transmit the command to the storage device;

store a host command credit in a host command register, the host command credit indicating an estimated command accommodation limit of the storage device;

store the response in a response slot; and

store a host response credit in a host response register, the host response credit indicating a limit of the response slot.

2. The electronic device of claim 1 , wherein the processing circuitry is further configured to

check an empty space of a command slot included in the storage device based on the host command credit, and

transmit the command and the host response credit to the storage device.

3. The electronic device of claim 1 , wherein the storage device comprises:

a storage response register configured to store a storage response credit indicating an estimated response accommodation limit of the host device;

a command slot configured to store the command;

a storage command register configured to store a storage command credit indicating a limit of the command slot; and

a storage controller configured to transmit the response to the host device.

4. The electronic device of claim 3 , wherein the storage controller is further configured to

insert the command into the command slot, and

update the storage response credit based on the host response credit.

5. The electronic device of claim 3 , wherein the storage controller is further configured to

check an empty space of the response slot based on the storage response credit, and

transmit the response and the storage command credit to the host device.

6. The electronic device of claim 5 , wherein the processing circuitry is further configured to

insert the response into the response slot, and

update the host command credit based on the storage command credit.

7. The electronic device of claim 1 , wherein

a first head pointer and a first tail pointer are referenced in the SQ,

a second head pointer and a second tail pointer are referenced in the CQ, and

the processing circuitry is further configured to store the first head pointer, the second head pointer, the first tail pointer, and the second tail pointer.

8. The electronic device of claim 7 , wherein the processing circuitry is further configured to

update the first tail pointer in accordance with storing the command in the SQ, and

update the first head pointer in accordance with transmitting the command to the storage device.

9. The electronic device of claim 8 , wherein the processing circuitry is further configured to

update the second tail pointer in accordance with storing the response in the CQ, and

update the second head pointer in accordance with performing the response.

10. The electronic device of claim 1 , wherein

the processing circuitry comprises a first core and a second core,

the first core is configured to process a first SQ and a first CQ, and

the second core is configured to process a second SQ and a second CQ.

11. The electronic device of claim 10 , wherein the processing circuitry is further configured to transmit, to the storage device, the command, the host response credit, an SQ ID indicating an SQ fetched by the processing circuitry, and a CQ ID indicating a CQ fetched by the processing circuitry.

12. The electronic device of claim 10 , wherein the processing circuitry is further configured to

select one of the first SQ and the second SQ, and

fetch a command stored in the selected SQ.

13. The electronic device of claim 10 , wherein the processing circuitry is further configured to

route a response stored in the response slot to a CQ selected from the first CQ and the second CQ.

14. The electronic device of claim 1 , wherein at least one of the SQ or the CQ is implemented as circular queue.

15. An operating method of a host device, the operating method comprising:

writing a command to at least one submission queue (SQ);

transmitting, to a storage device, the command and a host response credit, the host response credit indicating an actual response accommodation limit of the host device, the response accommodation limit of the host device based on a host command credit, the host command credit indicating an estimated command accommodation limit of the storage device;

receiving a response and a storage command credit from the storage device, the response being a result of performing the command, and the storage command credit indicating an actual command accommodation limit of the storage device;

updating the host command credit based on the storage command credit; and

writing the response to at least one completion queue (CQ).

16. The operating method of claim 15 , wherein

the writing the command comprises updating a tail pointer of the at least one SQ, and

the transmitting the command and the host response credit to the storage device comprises updating a head pointer of the at least one SQ.

17. The operating method of claim 15 , further comprising:

updating a head pointer of the at least one CQ as the written response is performed,

wherein the writing the response comprises updating a tail pointer of the at least one CQ.

18. The operating method of claim 15 , wherein

the at least one SQ comprises a first SQ to be processed by a first core of the host device and a second SQ to be processed by a second core of the host device,

the at least one CQ comprises a first CQ to be processed by the first core and a second CQ to be processed by the second core, and

the transmitting the command and the host response credit to the storage device comprises further transmitting an SQ ID indicating a fetched SQ.

19. The operating method of claim 18 , further comprising:

selecting one of the first SQ or the second SQ, and

fetching a command stored in the selected SQ.

20. The operating method of claim 18 , further comprising:

routing a response stored in a response slot included in the host device to a selected CQ from the first CQ and the second CQ.