TECHNIQUES FOR MOVING DATA BETWEEN MEMORY TYPES

• US 20130007345A1
• Filed: 07/01/2011
• Published: 01/03/2013
• Est. Priority Date: 07/01/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Sokol, Joseph Jr., BARBOU-DES-PLACES, FRANCOIS, Crane, Neil G., Desai, Lionel D.
• Granted Patent: US 9,195,581 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning
• CPC Class Codes: G06F 9/461 Saving or restoring of program or task context

Abstract

A two-level paging mechanism. The first level gathers data from reclaimable memory locations for a process and compacts the data into a single container. The second level sends the compact container'"'"'s contents to a swap file and may use optimal I/O operations to the target memory device. On-demand paging is made possible by having a first pager locate the requested data in the compact container and then having a second pager retrieve the corresponding data from the swap file.

Claims

1. A method comprising:

gathering data for a process from multiple reclaimable memory locations in a volatile memory;

copying one or more pointers to the data to a single container;

copying the data to a non-volatile memory using selected input/output (I/O) addresses.

2. The method of claim 1 wherein gathering data for a process from multiple reclaimable memory locations in a volatile memory comprises:

determining the memory locations corresponding to the process in a memory space of the volatile memory, wherein the memory space supports multiple concurrent processes;

walking the memory locations corresponding to the process;

determining if the respective memory locations are candidates for eviction from the volatile memory; and

recording pointers for memory locations that are candidates for eviction.

3. The method of claim 2 wherein memory locations that share pages between multiple processes are not candidates for eviction.

4. The method of claim 1 further comprising:

reclaiming the memory locations corresponding to the process; and

allocating the memory locations to another process.

5. The method of claim 1 wherein the container comprises a page of memory.

6. The method of claim 1 wherein the single container comprises a group of memory locations in an operating system kernel address space.

7. The method of claim 1 wherein the volatile memory comprises system random access memory (RAM) and the non-volatile memory comprises flash memory.

8. The method of claim 1 wherein the copying of the data to the non-volatile memory is accomplished in a single write operation to the non-volatile memory.

9. The method of claim 2 further comprising:

locating a page in the non-volatile memory having selected data; and

copying the page to the container.

10. The method of claim 9 further comprising:

locating an original location in the memory space; and

transferring the page to the original location.

11. The method of claim 9 wherein copying the page is accomplished in a single read operation to the volatile memory.

12. A computer-readable medium having stored thereon instructions that, when executed, cause one or more processors to:

gather data for a process from multiple reclaimable memory locations in a volatile memory;

copy one or more pointers to the data to a single container;

copy the data to a non-volatile memory using selected input/output (I/O) addresses.

13. The computer-readable medium of claim 12 wherein the instructions that cause the one or more processors to gather data for a process from multiple reclaimable memory locations in a volatile memory comprise instructions that, when executed, cause the one or more processors to:

determine the memory locations corresponding to the process in a memory space of the volatile memory, wherein the memory space supports multiple concurrent processes;

walk the memory locations corresponding to the process;

determine if the respective memory locations are candidates for eviction from the volatile memory; and

record pointers for memory locations that are candidates for eviction.

14. The computer-readable medium of claim 13 wherein memory locations that share pages between multiple processes are not candidates for eviction.

15. The computer-readable medium of claim 12 further comprising instructions that, when executed, cause the one or more processors to:

reclaim the memory locations corresponding to the process; and

allocate the memory locations to another process.

16. The computer-readable medium of claim 12 wherein the container comprises a page of memory.

17. The computer-readable medium of claim 12 wherein the single container comprises a group of memory locations in an operating system kernel address space.

18. The computer-readable medium of claim 12 wherein the volatile memory comprises system random access memory (RAM) and the non-volatile memory comprises flash memory.

19. The computer-readable medium of claim 12 wherein the copying of the data to the non-volatile memory is accomplished in a single write operation to the non-volatile memory.

20. The computer-readable medium of claim 12 further comprising instructions that, when executed, cause the one or more processors to:

locate a page in the non-volatile memory having selected data; and

copy the page to the container.

21. The computer readable medium of claim 20 further comprising instructions that, when executed, cause the one or more processors to:

locate an original location in the memory space; and

transfer the page to the original location.

22. The computer-readable medium of claim 20 wherein copying the page is accomplished in a single read operation to the non-volatile memory.

23. An apparatus comprising:

means for gathering data for a process from multiple reclaimable memory locations in a volatile memory;

means for copying one or more pointers to the data to a single container;

means for copying the data to a non-volatile memory using selected input/output (I/O) addresses.

24. The apparatus of claim 23 wherein the means for gathering data for a process from multiple reclaimable memory locations in a volatile memory comprises:

determining the memory locations corresponding to the process in a memory space of the volatile memory, wherein the memory space supports multiple concurrent processes;

means for walking the memory locations corresponding to the process;

means for determining if the respective memory locations are candidates for eviction from the volatile memory; and

means for recording pointers for memory locations that are candidates for eviction.

25. The apparatus of claim 23 further comprising:

means for reclaiming the memory locations corresponding to the process; and

means for allocating the memory locations to another process.

26. The apparatus of claim 23 further comprising:

means for locating a page in the non-volatile memory having selected data; and

means for copying the page to the container.

27. The apparatus of claim 26 further comprising:

means for locating an original location in the memory space; and

means for transferring the page to the original location.