System and method for high performance command processing in solid state drives
View Patent ↗Solid State Drives (SSD) can yield very high performance if it is designed properly. A SSD typically includes both a front end that interfaces with the host and a back end that interfaces with the flash media. Typically SSDs include flash media that is designed with a high degree of parallelism that can support a very high bandwidth on input/output (I/O). A SSD front end designed according to a traditional hard disk drive (HDD) model will not be able to take advantage of the high performance offered by the typical flash media. Embodiments of the invention provide improved management of multiple I/O threads that take advantage of the high performing and concurrent nature of the back end media, so the resulting storage system can achieve a very high performance.
1. A non-volatile memory storage system, comprising:
non-volatile storage comprising a plurality of solid-state storage devices; and
control circuitry configured to implement:
an interface to a host system, the interface configured to receive a plurality of commands from the host system; and
a data manager module configured to issue one or more data access requests to the non-volatile storage in response to instructions received from the interface based on the commands from the host system;
wherein the instructions are communicated via one of two data paths in the non-volatile memory storage system, the two data paths including:
a standard performance data path; and
a high performance data path comprising:
volatile memory for storing data control structures containing (1) the instructions from the interface to the data manager module and (2) responses to those instructions from the data manager module; and
a memory buffer for storing data that are to be transferred between the host system and the non-volatile storage, the data being associated with the commands received from the host system;
wherein the data manager module is configured to concurrently process a plurality of instructions from the interface stored in their associated data control structures; and
wherein each of the data control structures includes information related to processing of a command from the host system, wherein both the interface and the data manager module are configured to update the information independently, so that the processing of the command can be performed without delay due to copying of command related data from the interface to the data manager module.
2. The non-volatile memory storage system of claim 1 , wherein at least one of the data control structures is pre-configured with command processing information including information related to a data transfer size, so that a command requesting a data transfer size that is smaller than the pre-configured data transfer size can be serviced by the at least one pre-configured data control structure without additional processing to derive the pre-configured command processing information.
3. The non-volatile memory storage system of claim 1 , wherein each data control structure is associated with a pre-set buffer allocation from the memory buffer, the buffer allocation being used for receiving the data to be transferred for the command associated with the respective data control structure.
4. The non-volatile memory storage system of claim 1 , wherein the interface is configured to:
in response to receiving a data access command from the host system, communicate an instruction to the data manager module in one of the data control structures.
5. The non-volatile memory storage system of claim 4 , wherein the data access command is a write command and wherein the instruction is communicated to the data manager module ahead of the completion of transfer of data from the host system into the memory buffer, so that the processing of the command can take place concurrently with the transfer of data from the host system into the memory buffer.
6. The non-volatile memory storage system of claim 4 , wherein the data manager module is configured to:
upon detecting the instruction from the interface in one of the data control structures, process the instruction by performing one or more logical to physical mapping operations; and
when the instruction is for a write command, upon detection of completion of the transfer of the associated data in the memory buffer, issue a plurality of data access requests to the non-volatile storage so that the requests can be executed in parallel in the plurality of solid-state storage devices; and
when the instruction is for a read command, issue a plurality of data access requests to the non-volatile storage so that the requests can be executed in parallel in the plurality of solid-state storage devices.
7. The non-volatile memory storage system of claim 6 , wherein the data manager module is configured to:
coalesce status updates from the plurality of solid-state storage devices; and
update the data control structure associated with the instruction with information related to the coalesced status updates.
8. The non-volatile memory storage system of claim 7 , wherein the status updates include one or more of: an error notification and a completion notification.
9. The non-volatile memory storage system of claim 1 , wherein the plurality of solid-state storage devices comprise dies.
10. The non-volatile memory storage system of claim 1 , wherein the number of data control structures match a maximum number of commands from the host system that can be processed in the storage system at a given time, such that each command is associated with a data control structure.
11. The non-volatile memory storage system of claim 10 , wherein the maximum number of commands from the host system matches a queue depth in the non-volatile memory storage system that is used to receive commands from the host system in accordance with a specification.
12. The non-volatile memory storage system of claim 1 , wherein the control circuitry comprise one or more processors.
13. A method of processing commands in a solid-state storage system comprising non-volatile storage that comprises a plurality of solid-state storage devices, the method comprising:
receiving, by an interface, a plurality of commands from a host system; and
issuing, by a data manager module, one or more data access requests to the non-volatile storage in response to instructions that are sent by the interface based on the commands from the host system;
wherein the instructions are communicated via a high performance data path in the solid-state storage system, the high performing data path comprising:
volatile memory for storing data control structures containing (1) the instructions from the interface to the data manager module and (2) responses to those instructions from the data manager module; and
a memory buffer for storing data that are to be transferred between the host system and the non-volatile storage, the data being associated with the commands received from the host system; and
wherein each of data control structures includes information related to processing of one of the commands from the host system and is configured to be updated by both the interface and the data manager module.
14. The method of claim 13 , wherein at least one of the data control structures is pre-configured with command processing information including information related to a data transfer size, so that a command requesting a data transfer size that is smaller than the pre-configured data transfer size can be serviced by the at least one pre-configured data control structure without additional processing to derive the pre-configured command processing information.
15. The method of claim 13 , wherein each data control structure is associated with a pre-set buffer allocation from the memory buffer, the buffer allocation being used for receiving the data to be transferred for the command associated with the respective data control structure.
16. The method of claim 13 , further comprising:
in response to receiving a data access command from the host system, communicating, by the interface, an instruction to the data manager module in one of the data control structures.
17. The method of claim 16 , wherein the data access command is a write command and wherein the instruction is communicated to the data manager module ahead of the completion of transfer of data from the host system into the memory buffer.
18. The method of claim 16 , further comprising:
upon detecting the instruction from the interface in one of the data control structures, processing, by the data manager module, the instruction by performing one or more logical to physical mapping operations; and
when the instruction is for a write command, upon detection of completion of the transfer of the associated data in the memory buffer, issuing, by the data manager module, a plurality of data access requests to the non-volatile storage so that the requests can be executed in parallel in the plurality of solid-state storage devices; and
when the instruction is for a read command, issuing, by the data manager module, a plurality of data access requests to the non-volatile storage so that the requests can be executed in parallel in the plurality of solid-state storage devices.
19. The method of claim 18 , further comprising:
coalescing, by the data manager module, status updates from the plurality of solid-state storage devices; and
updating, by the data manager module, the data control structure associated with the instruction with information related to the coalesced status updates.
20. The method of claim 19 , wherein the status updates include one or more of: an error notification and a completion notification.
21. The method of claim 13 , further comprising: concurrently processing, by the data manager module, a plurality of instructions from the interface stored in their associated data control structures.
22. A non-volatile memory storage system, comprising:
non-volatile storage comprising a plurality of solid-state storage devices;
control circuitry configured to implement:
an interface to a host system, the interface configured to receive a plurality of commands from the host system; and
a data manager module configured to:
issue one or more data access requests to the non-volatile storage in response to instructions sent by the interface based on the commands from the host system; and
volatile memory configured to store data control structures through which said instructions are communicated, the data control structures comprising information related to processing of said commands from the host system, wherein both the interface and the data manager module are configured to update said information independently.
23. The non-volatile memory storage system of claim 22 , wherein at least one of the data control structures is pre-configured with command processing information including information related to a pre-set data transfer size, so that a command requesting a data transfer size that is smaller than the pre-set data transfer size can be serviced by the at least one pre-configured data control structure without additional processing to derive the pre-configured command processing information.