EXTENDED PAGE SIZE USING AGGREGATED SMALL PAGES

• US 20110004739A1
• Filed: 07/01/2009
• Published: 01/06/2011
• Est. Priority Date: 07/01/2009
• Status: Active Grant

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Friebel, Thomas, Biemueller, Sebastian, Dannowski, Uwe M., Hohmuth, Michael P., Diestelhorst, Stephan, Christie, David S.
• Granted Patent: US 8,195,917 B2
• Time in Patent Office: Days
• US Class Current: 711/207
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 12/1027 using associative or pseudo-associative address translation means, e.g. translation look-aside buffer [TLB]
• CPC Class Codes: G06F 2212/652 Page size control

Abstract

A processor including a virtual memory paging mechanism. The virtual memory paging mechanism enables an operating system operating on the processor to use pages of a first size and a second size, the second size being greater than the first size. The mechanism further enables the operating system to use superpages including two or more contiguous pages of the first size. The size of a superpage is less than the second size. The processor further includes a page table having a separate entry for each of the pages included in each superpage. The operating system accesses each superpage using a single virtual address. The mechanism interprets a single entry in a translation lookaside buffer TLB as referring to a region of memory comprising a set of pages that correspond to a superpage in response to detecting a superpage enable indicator associated with the entry in the TLB is asserted.

Claims

1. A processor comprising:

a virtual memory paging mechanism, wherein the virtual memory paging mechanism is configured to enable an operating system operating on the processor to;

use pages of a first size and pages of a second size, the second size being greater than the first size;

form superpages comprising a set of pages including two or more contiguous pages of the first size, wherein a size of a superpage is less than the second size; and

a page table that includes a separate entry for each of the two or more contiguous pages included in each superpage.

2. The processor of claim 1, wherein the virtual memory paging mechanism is further configured to enable the operating system operating on the processor to access each superpage using a single virtual address.

3. The processor of claim 1, wherein the size of a superpage is 64 KB.

4. The processor of claim 2, further comprising a translation lookaside buffer (TLB), wherein the virtual memory paging mechanism is configured to interpret a single entry in the TLB as referring to a region of memory comprising a set of pages that correspond to a superpage in response to detecting a superpage enable indicator associated with the entry in the TLB is asserted.

5. The processor of claim 4, wherein the virtual memory paging mechanism is further configured to interpret an entry in the page table as referring to a region of memory comprising a portion of a superpage, in response to detecting a superpage enable indicator associated with the entry in the page table is asserted.

6. The processor of claim 4, wherein the superpage enable indicator is software-settable.

7. The processor of claim 2, wherein the virtual memory paging mechanism is further configured to issue a page fault in response to detecting that at least one of the at least two entries in the page table is missing or includes attributes that are not consistent with corresponding attributes in other of the at least two entries in the page table.

8. The processor of claim 1, wherein the virtual memory paging mechanism is further configured to simultaneously and independently enable the use of superpages on one or both of a first operating system and a second operating system operating on the processor.

9. The processor of claim 8, wherein the first operating system is a guest operating system in a virtualized environment configured to use a first page table to translate a virtual address in guest address space to a physical address in guest address space and the second operating system is a host operating system in a virtualized environment configured to use a second page table to translate a physical address in guest address space to a physical address in host address space.

10. The processor of claim 1, wherein the virtual memory paging mechanism is further configured to enable the operating system to use superpages of two or more different superpage sizes, wherein each superpages size is equal to a size of two or more contiguous, aligned pages of the first size and wherein each superpage size is less than the second size.

11. A method for virtual memory paging in a processor, the method comprising:

enabling an operating system operating on the processor to use pages of a first size and pages of a second size, the second size being greater than the first size; and

enabling the operating system to form superpages comprising a set of pages including two or more contiguous pages of the first size, wherein a size of a superpage is less than the second size; and

including a separate entry in a page table for each of the two or more contiguous pages included in each superpage.

12. The method of claim 11, further comprising enabling the operating system operating on the processor to access each superpage using a single virtual address.

13. The method of claim 11, wherein the size of a superpage is 64 KB.

14. The method of claim 12, further comprising interpreting a single entry in a TLB as referring to a region of memory comprising a set of pages that correspond to a superpage in response to detecting a superpage enable indicator associated with the entry in the TLB is asserted.

15. The method of claim 14, further comprising interpreting an entry in the page table as referring to a region of memory comprising a portion of a superpage in response to detecting a superpage enable indicator associated with the entry in the page table is asserted.

16. The method of claim 14, wherein the superpage enable indicator is software-settable.

17. The method of claim 12, further comprising issuing a page fault in response to detecting that at least one of the at least two entries in the page table is missing or includes attributes that are not consistent with corresponding attributes in other of the at least two entries in the page table.

18. The method of claim 11, further comprising simultaneously and independently enabling the use of superpages on one or both of a first operating system and a second operating system operating on the processor.

19. The method of claim 18, wherein the first operating system is a guest operating system in a virtualized environment configured to use a first page table to translate a virtual address in guest address space to a physical address in guest address space and the second operating system is a host operating system in a virtualized environment configured to use a second page table to translate a physical address in guest address space to a physical address in host address space.

20. The method of claim 11, further comprising enabling the operating system to use superpages of two or more different superpage sizes, wherein each superpages size is equal to a size of two or more contiguous, aligned pages of the first size and wherein each superpage size is less than the second size.