ADAPTIVE HOST MEMORY BUFFER (HMB) CACHING USING UNASSISTED HINTING

• US 20160246726A1
• Filed: 02/22/2016
• Published: 08/25/2016
• Est. Priority Date: 08/20/2014
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Hahn, Judah Gamliel
• Granted Patent: US 10,268,584 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 2206/1014 One time programmable [OTP] memory, e.g. PROM, WORM
• CPC Class Codes: G06F 2212/1021 Hit rate improvement
• CPC Class Codes: G06F 2212/1024 Latency reduction
• CPC Class Codes: G06F 2212/2022 Flash memory
• CPC Class Codes: G06F 2212/281 Single cache
• CPC Class Codes: G06F 2212/311 In host system
• CPC Class Codes: G06F 2212/466 Metadata, control data
• CPC Class Codes: G06F 2212/6028 Prefetching based on hints or prefetch instructions
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A storage device includes a nonvolatile memory. The storage device further includes a hint derivation module for automatically deriving, from host accesses to the storage device, hints regarding expected future host accesses to a table that maps logical memory addresses to physical memory addresses in the nonvolatile memory. The storage device further includes an adaptive host memory buffer (HMB) caching module for using the hints to identify portions of the table to cache in the HMB and for caching the identified portions in the HMB, which is external to the storage device and accessible by the storage device via a bus.

Claims

1. A storage device comprising:

nonvolatile memory; and

a hint derivation module for automatically deriving, from host accesses to the storage device, hints regarding expected future host accesses to a table that maps logical memory addresses to physical memory addresses in the nonvolatile memory; and

an adaptive host memory buffer (HMB) caching module for using the hints to identify portions of the table to cache in the HMB and for caching the identified portions in the HMB, which is external to the storage device and accessible by the storage device via a bus.

2. The storage device of claim 1 wherein the nonvolatile memory comprises flash memory.

3. The storage device of claim 2 wherein the flash memory comprises NAND flash memory or NOR flash memory having a two-dimensional or three-dimensional configuration.

4. The storage device of claim 1 wherein the nonvolatile memory includes solid state memory and at least one disk storage device.

5. The storage device of claim 1 wherein the hint derivation module is configured to identify a file affected by the host accesses to the storage device and the adaptive HMB caching module is configured to cache entries in the table associated with the file in the HMB.

6. The storage device of claim 1 wherein the table comprises a flash translation layer (FTL) table and wherein the adaptive HMB caching module is configured to maintain a primary FTL cache in static random access memory associated with the storage device and a secondary FTL cache in the HMB.

7. The storage device of claim 6 wherein the adaptive HMB caching module is configured to store entries from the FTL table that are expected to be accessed next by a read command in the primary FTL cache and to store FTL table entries expected to be accessed later in the secondary FTL cache.

8. The storage device of claim 7 wherein the hint derivation module is configured to identify one of the host system accesses to the nonvolatile memory as a read command for a video file and wherein the adaptive HMB caching module is configured to cache FTL table entries associated with a next few frames of the video file in the primary FTL cache and to cache FTL table entries associated with a remainder of the video file in the secondary FTL cache.

9. The storage device of claim 1 wherein the hint derivation module is configured to derive the hints in-line or asynchronously with the host accesses to the storage device.

10. A method comprising:

in a storage device including nonvolatile memory;

automatically deriving, from host accesses to the storage device, hints regarding expected future host accesses to a table that maps logical memory addresses to physical memory addresses in the nonvolatile memory; and

using the hints to identify portions of the table to cache in the HMB; and

caching the identified portions in the HMB, which is external to and accessible by the storage device via a bus.

11. The method of claim 10 wherein the nonvolatile memory comprises flash memory.

12. The method of claim 11 wherein the flash memory comprises NAND flash memory or NOR flash memory having a two-dimensional or three-dimensional configuration.

13. The method of claim 10 wherein the nonvolatile memory includes solid state memory and at least one disk storage device.

14. The method of claim 10 wherein automatically deriving the hints includes identifying a file affected by the host accesses to the storage device and wherein using the hints includes caching entries in the table associated with the file in the HMB.

15. The method of claim 10 wherein the table comprises a flash translation layer (FTL) table and wherein the method further comprises maintaining a primary FTL cache in static random access memory associated with the storage device and a secondary FTL cache in the HMB.

16. The method of claim 15 comprising storing entries from the FTL table that are expected to be accessed next by a read command in the primary FTL cache and storing FTL table entries expected to be accessed later in the secondary FTL cache.

17. The method of claim 16 wherein automatically deriving the hints includes identifying one of the accesses to the nonvolatile memory as a read command for a video file and wherein using the hints comprises FTL table entries associated with a next few frames of the video file in the primary FTL cache and to cache FTL table entries associated with a remainder of the video file in the secondary FTL cache.

18. The method of claim 10 wherein automatically deriving the hints includes deriving the hints in-line or asynchronously with the accesses to the nonvolatile memory.

19. A nontransitory computer readable media having stored thereon executable instructions that when executed by the processor of a computer control the computer to perform steps comprising:

in a storage device including nonvolatile memory;

automatically deriving, from host accesses to the storage device, hints regarding expected future host accesses to a table that maps logical memory addresses to physical memory addresses in the nonvolatile memory;

using the hints to identify portions of the table to cache in the HMB; and

caching the identified portions in the HMB, which is external to and accessible to the storage device via a bus.