Doorbell-less protocol for solid state drive interface

Patent metadata

Field	Value
Publication number	US-9652199-B2
Application number	US-201414489994-A
Country	US
Kind code	B2
Filing date	Sep 18, 2014
Priority date	Sep 18, 2013
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

The present disclosure relates to methods and systems for performing operations in a communications protocol. An example method can include submitting, from a device, a request for a queue entry representing a command from a host comprising a request for data stored at a device memory location; receiving the command from the host; and executing the command. An example method can also include selecting a bit string representing whether a requested data stream has been received, and storing the bit string into a memory buffer portion to mark the buffer portion. The method can include receiving, into the memory buffer, the stream. The method can include retrieving contents of the buffer portion, and determining whether the contents contain the bit string. If so, the method can include determining that portions of the stream have not been received. Otherwise, the method can include determining that the stream has been received.

First claim

What is claimed is:

1. A method of performing operations in a communications protocol, the method comprising:
submitting, from a target in communication with a host via the communications protocol, a command request for an entry in a queue, wherein the entry in the queue represents a command inserted into the queue by the host, wherein submitting the command request for the entry comprises submitting the command request without receiving, from the host, a command availability signal prior to submitting the command request;
receiving, by the target responsive to the command request, the entry in the queue, wherein the received entry in the queue comprises the command inserted into the queue by the host, and wherein the command comprises a request for data; and
executing, by the target, the command to provide the requested data, responsive to the received entry in the queue.

2. The method of claim 1 , wherein the command availability signal indicates that the host has inserted the command into the queue for processing by the target.

3. The method of claim 2 , further comprising processing a completion of the entry in the queue without writing a completion entry to a completion queue on the host and without generating an interrupt.

4. The method of claim 2 , further comprising:
determining a time for submitting a subsequent command request, based on predicting an arrival time of a subsequent command into the queue; and
submitting, from the target at the determined time, a subsequent command request for a subsequent entry in the queue on the host without receiving, from the host, a subsequent command availability signal prior to submitting the subsequent command request.

5. The method of claim 4 , wherein predicting the arrival time of the subsequent command into the queue is based on predicting a latency of time elapsed between submitting the command request for the entry in the queue and receiving the requested entry in the queue; and
wherein submitting the subsequent command request is interleaved with providing the requested data from the target.

6. A method of performing operations in a communications protocol, the method comprising:
submitting, from a target in communication with a host via the communications protocol, a command request for an entry in a queue, wherein the entry in the queue represents a command inserted into the queue by the host;
receiving, by the target responsive to the command request, the entry in the queue, wherein the received entry in the queue comprises the command inserted into the queue by the host, and wherein the command comprises a request for data;
executing, by the target, the command to provide the requested data, responsive to the received entry in the queue;
receiving, from the host, a command availability signal, wherein the command availability signal indicates that the host has inserted an initial command into the queue for processing by the target;
submitting, from the target responsive to the command availability signal, an initial command request for an initial entry in the queue, wherein the initial entry in the queue represents the initial command inserted into the queue by the host;
receiving, from the host responsive to the initial command request, the initial entry in the queue, wherein the received initial entry in the queue includes the initial command inserted into the queue by the host, and wherein the initial command includes an initial request for data stored at an initial device memory location;
executing the initial command to provide the requested initial data from the target, responsive to the received entry in the queue; and
receiving, from the host, a command to switch a communication mode based on a pre-determined measure of input/output operations per second (IOPS), wherein the communication mode causes the target to submit a subsequent command request for a subsequent entry in the queue without receiving, from the host, a subsequent command availability signal.

7. The method of claim 1 , wherein the operations in the communication protocol comprise read operations.

8. The method of claim 1 , wherein the communication protocol includes commands with command formats compatible with the Non-Volatile Memory Express standard.

9. The method of claim 1 , wherein the requested data is stored in a storage in communication with the target.

10. The method of claim 9 , wherein the storage comprises a phase-change memory.

11. A system for performing operations in a communications protocol, the system comprising:
a host in communication with a memory; and
a target in communication with the host via the communication protocol, for transmitting a requested data;
wherein the target is configured to:
submit to the memory a command request for an entry in a queue, wherein the entry in the queue represents a command inserted into the queue by the host, wherein the target is configured to submit the command request for the entry by submitting the command request without receiving, from the host, a command availability signal prior to submitting the command request;
receive, responsive to the command request, the entry in the queue, wherein the received entry in the queue comprises the command inserted into the queue by the host, and wherein the command comprises a request for data; and
execute the command to provide the requested data from the target, responsive to the received entry in the queue.

12. The system of claim 11 , wherein the command availability signal indicates that the host has inserted the command into the queue for processing by the target.

13. The system of claim 12 , wherein the target is further configured to process a completion of the entry in the queue without writing a completion entry to a completion queue on the host and without generating an interrupt.

14. The system of claim 12 , the target is further configured to:
determine a time for submitting a subsequent command request, based on predicting an arrival time of a subsequent command into the queue; and
submit at the determined time, a subsequent command request for a subsequent entry in the queue on the host without receiving, from the host, a subsequent command availability signal prior to submitting the subsequent command request.

15. The system of claim 14 ,
wherein predicting the arrival time of the subsequent command into the queue is based on predicting a latency of time elapsed between submitting the command request for the entry in the queue and receiving the requested entry in the queue; and
wherein the target is configured to submit the subsequent command request interleaved with providing the requested data from the target.

16. A system for performing operations in a communications protocol, the system comprising:
a host in communication with a memory; and
a target in communication with the host via the communication protocol, for transmitting a requested data;
wherein the target is configured to:
submit to the memory a command request for an entry in a queue, wherein the entry in the queue represents a command inserted into the queue by the host;
receive, responsive to the command request, the entry in the queue, wherein the received entry in the queue comprises the command inserted into the queue by the host, and wherein the command comprises a request for data;
execute the command to provide the requested data from the target, responsive to the received entry in the queue;
receive from the host, a command availability signal, wherein the command availability signal indicates that the host has inserted an initial command into

Assignees

• Western Digital Tech Inc

Inventors

• Vucinic Dejan
• Bandic Zvonimir Z
• Wang Qingbo
• Guyot Cyril
• Mateescu Robert
• Chu Frank R

Classifications

• G06F13/385 Primary

  for adaptation of a particular data processing system to different peripheral devices · CPC title

• G06F3/0659

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title

• G06F3/0656

  Data buffering arrangements · CPC title

• G06F3/0679

  Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP] · CPC title

• G06F3/061

  Improving I/O performance · CPC title