Granted Patent B2

US 10,956,083 · App. 15/693,021 · Granted Mar 23, 2021

Abstract

Claims (91)

1. A method of processing, in a non-volatile memory system, memory operations requested by a host system, comprising:

receiving host requests that each specify a memory operation to be performed by the non-volatile memory system, the specified memory operations including read operations and write operations; and

performing a set of operations for each memory operation specified by a received host request, including:

initiating performance of the memory operation;

determining a first factor corresponding to available space in a write cache of the non-volatile memory system;

determining a second factor corresponding to a write prevalence metric indicating a percentage of the memory operations specified by the received host requests that are the write operations;

determining a throttle interval for the memory operation from a throttle interval lookup table by:

determining a throttle index based on the second factor;

selecting a record of the throttle interval lookup table using the throttle index, wherein each record of the throttle interval lookup table comprises a throttle interval value for a read operation and a throttle interval value for a write operation; and

using the first factor to select a particular throttle interval value from the selected record; and

returning to the host system a response associated with the memory operation at time no earlier than a start time associated with the memory operation plus the determined throttle interval.

2. The method of claim 1 , wherein:

the first factor is determined in accordance with a weighted sum of two or more factors;

the two or more factors include the second factor and a third factor; and

the third factor corresponds to a ratio of non-host write operations to host write operations in the non-volatile memory system.

3. The method of claim 1 , wherein:

the throttle interval lookup table includes three or more records;

each record corresponds to a different value of the throttle index;

each record includes a plurality of throttle interval values; and

determining the throttle interval includes selecting, in accordance with the first factor, a throttle interval value from among the plurality of throttle interval values in a record of the throttle interval lookup table identified by the throttle index.

4. The method of claim 3 , wherein the throttle interval values included in the three or more records of the throttle interval lookup table include:

at least one value corresponding to a throttle interval of zero duration; and

a maximum value corresponding to a throttle interval of at least one millisecond.

5. The method of claim 1 , further comprising storing, for each memory operation specified by a received host request, a timestamp representing the start time associated with the memory operation.

6. The method of claim 1 , further comprising:

providing responses to requests specifying read operations that satisfy a predefined quality of service standard for read operations; and

providing responses to requests specifying write operations that satisfy a predefined quality of service standard for write operations.

7. The method of claim 1 , wherein:

responsive to the memory operation comprising a read operation, the response indicates that the read operation to non-volatile memory has been completed and that read data is ready to be sent to the host system; and

responsive to the memory operation comprising a write operation, the response indicates that write data has been stored in the write cache but not in non-volatile memory.

8. The method of claim 7 , wherein:

the read operation is completed before the time no earlier than the start associated with the memory operation plus the determined throttle interval; and

the write operation is completed after the time no earlier than the start time associated with the memory operation plus the determined throttle interval.

9. A non-volatile memory system, comprising:

non-volatile memory;

one or more processors; and

memory storing one or more programs that, when executed by the one or more processors, cause the non-volatile memory system to:

receive, from a host system, host requests that each specify a memory operation to be performed by the non-volatile memory system, the specified memory operations including read operations and write operations; and

perform a set of operations for each memory operation specified by a received host request, including:

initiating performance of the memory operation;

determining a first factor corresponding to available space in a write cache of the non-volatile memory system;

determining a second factor corresponding to a write prevalence metric indicating a percentage of the memory operations specified by the received host requests that are the write operations;

determining a throttle interval for the memory operation from a data structure by:

determining a throttle index based on the second factor;

selecting a record in the data structure using the throttle index, wherein each record of the data structure comprises a throttle interval value for a read operation and a throttle interval value for a write operation; and

using the first factor to select a particular throttle interval value from the selected record; and

delaying transmission to the host system of a response associated with the memory operation when a current time is less than a sum of a start time associated with the memory operation and the determined throttle interval.

10. The non-volatile memory system of claim 9 , wherein the non-volatile memory comprises a three-dimensional memory array.

11. The non-volatile memory system of claim 9 , wherein:

the first factor is determined in accordance with a weighted sum of two or more factors;

the two or more factors include the second factor and a third factor; and

the third factor corresponds to a ratio of non-host write operations to host write operations in the non-volatile memory system.

12. The non-volatile memory system of claim 11 , wherein the one or more programs are further configured to cause the non-volatile memory system to select one of a plurality of records based on the weighted sum of the two or more factors.

13. The non-volatile memory system of claim 12 , wherein:

the plurality of records comprise at least three records; and

the throttle interval values included in the plurality of records of the data structure include:

at least one value corresponding to a throttle interval of zero duration; and

a maximum value corresponding to a throttle interval of at least one millisecond.

14. The non-volatile memory system of claim 9 , wherein the one or more programs are further configured to cause the non-volatile memory system to store, for each memory operation specified by a received host request, a timestamp representing the start time associated with the memory operation.

15. The non-volatile memory system of claim 9 , wherein the one or more programs are further configured to cause the non-volatile memory system to:

provide responses to requests specifying read operations that satisfy a predefined quality of service standard for read operations; and

provide responses to requests specifying write operations that satisfy a predefined quality of service standard for write operations.

16. The non-volatile memory system of claim 15 , wherein the predefined quality of service standard for read operations comprises a read response time requirement that is less than a write response time requirement for the predefined quality of service standard for write operations.

17. The non-volatile memory system of claim 9 , wherein:

responsive to the memory operation comprising a read operation, the response indicates that the read operation to non-volatile memory has been completed and that read data is ready to be sent to the host system; and

responsive to the memory operation comprising a write operation, the response indicates that write data has been stored in the write cache but not in non-volatile memory.

18. The non-volatile memory system of claim 17 , wherein:

the read operation is completed before the time no earlier than the start time associated with the memory operation plus the determined throttle interval; and

the write operation is completed after the time no earlier than the start time associated with the memory operation plus the determined throttle interval.

19. A non-volatile memory system, comprising:

a non-volatile memory;

means for receiving host requests that each specify a memory operation to be performed by the non-volatile memory system, the specified memory operations including read operations and write operations; and

means for performing a set of operations for each memory specified by a received host request, including:

means for initiating performance of the memory operation;

means for determining a first factor corresponding to available space in a write cache of the non-volatile memory system;

means for determining a second factor corresponding to a write prevalence metric indicating a percentage of the memory operations specified by the received host requests that are the write operations;

means for determining a throttle interval for the memory operation from a throttle interval lookup table by:

determining a throttle index based on the second factor;

selecting a record of the throttle interval lookup table using the throttle index, wherein each record of the throttle interval lookup table comprises a throttle interval value for a read operation and a throttle interval value for a write operation; and

using the first factor to select a particular throttle interval value from the selected record; and

means for delaying transmission to a host system a response associated with the memory operation until a time no earlier than a start time associated with the memory operation plus the determined throttle interval.

20. The non-volatile memory system of claim 19 , wherein:

the means for determining a throttle interval is further configured to determine the first factor in accordance with a weighted sum of two or more factors;

the two or more factors include the second factor and a third factor; and

the third factor corresponds to a ratio of non-host write operations to host write operations in the non-volatile memory system.

21. The non-volatile memory system of claim 19 , wherein:

responsive to the memory operation comprising a read operation, the response indicates that the read operation to non-volatile memory has been completed and that read data is ready to be sent to the host system; and

responsive to the memory operation comprising a write operation, the response indicates that write data has been stored in the write cache but not in non-volatile memory.

22. The non-volatile memory system of claim 21 , wherein:

the read operation is completed before the time no earlier than the start time associated with the memory operation plus the determined throttle interval; and

the write operation is completed after the time no earlier than the start time associated with the memory operation plus the determined throttle interval.

Assignments (10)