Computer system with virtual memory and paging mechanism

• US 6,970,991 B2
• Filed: 09/11/2002
• Issued: 11/29/2005
• Est. Priority Date: 11/07/2001
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Harman, Philip
• Primary Examiner(s): Thai, Tuan V.
• Assistant Examiner(s): Patel, Hetul
• Application Number:
  US10/241,178
• Publication Number:
  US 20030088752A1
• Time in Patent Office: 1,175 Days
• Field of Search: 711/203, 711206-209
• US Class Current: 711/206
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 2212/652 Page size control
• CPC Class Codes: G06F 9/5016 the resource being the memory

Abstract

A computer system supports virtual memory and a paging mechanism. When a new process is created, this occupies one or more memory region. In one embodiment, at least a first memory region occupied by the process at a first virtual address has predefined, fixed, page characteristics (for example page size). It turns out that these are not optimum for the performance of the process. In order to address this, a routine in a shared library is invoked to copy the component from the first memory region into a second memory region. The second memory region either has different page characteristics from the first memory region (for example, a different page size), or is modifiable to have such different page characteristics. The second memory region is reallocated in virtual memory so that it replaces the first memory region at the first virtual address. The overall consequence of this is that at least one component of the process can now operate at a more suitable page characteristic (such as page size), thereby leading to improved performance.

Claims

1. A method of operating a computer system supporting virtual memory and a paging mechanism, said method comprising the steps of:

creating a process in memory, said process including at least one component in a first pageable memory region having a first paging characteristic, said first memory region being located at a first virtual address, wherein said first memory region comprises one or more memory segments, wherein the first memory region comprises a process heap segment;

expanding the heap segment;

making a copy in virtual memory of said at least one component at a virtual address different from said first virtual address after said expanding the heap segment;

retaining a portion of the heap in said first memory region having the first paging characteristic; and

replacing the first memory region at the first virtual address with a second pageable memory region having a second paging characteristic, wherein said second memory region comprises one or more memory segments;

wherein said copy of the at least one component is stored in the second memory region having the second paging characteristic.

2. The method of claim 1, wherein the step of making a copy of said at least one component comprises copying said at least one component into said second memory region.

3. The method of claim 2, further comprising the step of attaching the second memory region to a second virtual address of the process prior to performing said copying step, and wherein said step of replacing the first memory region at the first virtual address with the second memory region comprises the steps of detaching the second memory region from said second virtual address and attaching the second memory region to said first virtual address.

4. The method of claim 1, wherein the step of making a copy of said at least one component comprises copying said at least one component into a third memory region having a virtual address different from said first virtual address, and said method further comprises the step of duplicating said at least one component from the third memory region into the second memory region after performing the step of replacing the first memory region at the first virtual address with the second memory region.

5. The method of claim 4, further comprising the step of deleting the third memory region after performing said duplicating step.

6. The method of claim 1, wherein said step of replacing includes the step of detaching the first memory region from said first virtual address.

7. The method of claim 1, wherein said first paging characteristic represents a first page size.

8. The method of claim 7, wherein said second paging characteristic represents a second page size, whereby said second page size is substantially larger than said first page size.

9. The method of claim 1, wherein a the first memory region comprises a process text segment.

10. The method of claim 1, wherein the first memory region comprises a process data segment.

11. The method of claim 1, wherein said steps of making a copy and replacing the first memory region are performed prior to execution of the main body of process code itself.

12. The method of claim 11, wherein said steps of making a copy and replacing the first memory region are implemented by calling a shared library which is dynamically linked to said process at run-time.

13. The method of any of claim 1, further comprising the step of quiescing the process prior to performing the steps of making a copy and replacing the first memory region.

14. A computer system supporting virtual memory and a paging mechanism, and including:

means for creating a process in memory, said process including at least one component in a first pageable memory region having a first paging characteristic, said first memory region being located at a first virtual address, wherein said first memory region comprises one or more memory segments, wherein the first memory region comprises a process heap segment;

means for expanding the heap segment;

means for making a copy in virtual memory of said at least one component at a virtual address different from said first virtual address after expanding the heap segment;

means for retaining a portion of the heap in said first memory region having the first paging characteristic; and

means for replacing the first memory region at the first virtual address with a second pageable memory region having a second paging characteristic, wherein said second memory region comprises one or more memory segments;

wherein said copy of the at least one component is stored in the second memory region having the second paging characteristic.

15. The computer system of claim 14, wherein the means for making a copy includes means for copying said at least one component into said second memory region.

16. The computer system of claim 15, further comprising means for attaching the second memory region to a second virtual address of the process prior to performing said copying, and wherein said means for replacing the first memory region at the first virtual address with the second memory region comprises the means for detaching the second memory region from said second virtual address and means for attaching the second memory region to said first virtual address.

17. The computer system of claim 14, wherein the means for making a copy of said at least one component comprises means for copying said at least one component into a third memory region having a virtual address different from said first virtual address, and said computer system further comprises means for duplicating said at least one component from the third memory region into the second memory region after replacing the first memory region at the first virtual address with the second memory region.

18. The computer system of claim 17, further comprising the means for deleting the third memory region after said duplicating.

19. The computer system of claim 14, wherein said means for replacing includes means for detaching the first memory region from said first virtual address.

20. The computer system of claim 14, wherein said first paging characteristic represents a first page size.

21. The computer system of claim 20, wherein said second paging characteristic represents a second page size, whereby said second page size is substantially larger than said first page size.

22. The computer system of claim 14, wherein the first memory region comprises a process text segment.

23. The computer system of claim 14, wherein the first memory region comprises a process data segment.

24. The computer system of claim 14, wherein said means for making a copy and means for replacing the first memory region are operative prior to execution of the main body of process code itself.

25. The computer system of claim 24, wherein said means for making a copy and means for replacing the first memory region are implemented by calling a shared library which is dynamically linked to said process at run-time.

26. The computer system of claim 14, further comprising means for quiescing the process prior to making a copy and replacing the first memory region.

27. A computer program product comprising instructions in machine readable form on a storage medium, said instructions when loaded into a computer system supporting virtual memory and a paging mechanism operable to make the system perform a method comprising the steps of:

creating a process in memory, said process including at least one component in a first pageable memory region having a first paging characteristic, said first memory region being located at a first virtual address, wherein said first memory region comprises one or more memory segments, wherein the first memory region comprises a process heap segment;

expanding the heap segment;

making a copy in virtual memory of said at least one component at a virtual address different from said first virtual address after said expanding the heap segment;

retaining a portion of the heap in said first memory region having the first paging characteristic; and

replacing the first memory region at the first virtual address with a second pageable memory region having a second paging characteristic, wherein said second memory region comprises one or more memory segments;

wherein said copy of the at least one component is stored in the second memory region having the second paging characteristic.

28. The computer program product of claim 27, wherein the step of making a copy of said at least one component comprises copying said at least one component into said second memory region.

29. The computer program product of claim 28, further comprising instructions operable to make the computer perform the step of attaching the second memory region to a second virtual address of the process prior to performing said copying step, and wherein said step of replacing the first memory region at the first virtual address with the second memory region comprises the steps of detaching the second memory region from said second virtual address and attaching the second memory region to said first virtual address.

30. The computer program product of claim 27, wherein the step of making a copy of said at least one component comprises copying said at least one component into a third memory region having a virtual address different from said first virtual address, and said computer program product further comprises instructions operable to make the computer perform the step of duplicating said at least one component from the third memory region into the second memory region after performing the step of replacing the first memory region at the first virtual address with the second memory region.

31. The computer program product of claim 30, further comprising instructions operable to make the computer perform the step of deleting the third memory region after performing said duplicating step.

32. The computer program product of claim 27, wherein said step of replacing includes the step of detaching the first memory region from said first virtual address.

33. The computer program product of claim 27, wherein said first paging characteristic represents a first page size.

34. The computer program product of claim 33, wherein said second paging characteristic represents a second page size, whereby said second page size is substantially larger than said first page size.

35. The computer program product of claim 27, wherein the first memory region comprises a process text segment.

36. The computer program product of claim 27, wherein the first memory region comprises a process data segment.

37. The computer program product of claim 27, wherein said steps of making a copy and replacing the first memory region are performed prior to execution of the main body of process code itself.

38. The computer program product of claim 37, wherein said steps of making a copy and replacing the first memory region are implemented by calling a shared library which is dynamically linked to said process at run-time.

39. The computer program product of claim 27, further comprising instructions operable to make the computer perform the step of quiescing the process prior to performing the steps of making a copy and replacing the first memory region.

40. A computer system supporting virtual memory and a paging mechanism, and comprising:

a process including at least one component in a first pageable memory region having a first paging characteristic, said first memory region being located at a first virtual address and comprising a process heap segment;

a duplication routine for application to said at least one component to make a copy in virtual memory of said at least one component at a virtual address different from said first virtual address, wherein the copy is made after expanding the process heap segment; and

a second pageable memory region having a second paging characteristic;

wherein the first memory region at the first virtual address is replaced with said second memory region, wherein said copy of the at least one component is stored in the second memory region having the second paging characteristic, and wherein a portion of the process heap segment is retained in the first memory region having the first paging characteristic.

41. A method of operating a computer system supporting virtual memory and a paging mechanism, said method comprising the steps of:

creating a process in memory, said process including at least one component in a first pageable memory region having a first paging characteristic, said first memory region being located at a first virtual address and comprising a process heap segment;

expanding the process heap segment;

copying said at least one component from said first memory region into a second pageable memory region having a second paging characteristic, thereby making a copy of said at least one component in virtual memory at a virtual address different from said first virtual address; and

reallocating the second memory region in virtual memory so that it replaces the first memory region at said first virtual address while retaining the second paging characteristic, wherein a portion of the process heap segment is retained in the first memory region having the first paging characteristic.

42. A method of operating a computer system having at least first and second processors and a non-uniform memory architecture, and supporting virtual memory and a paging mechanism, said method comprising the steps of:

storing process code for the first processor in a first pageable memory region comprising a process heap segment;

expanding the process heap segment;

making a copy in virtual memory of said process code in a second pageable memory region;

replacing the first memory region for the second processor with the second memory region at the same virtual address;

wherein said first and second memory regions have different latencies from the perspective of the second processor, and wherein a portion of the process heap segment is retained in the first memory region having the first paging characteristic.

43. A computer system having at least first and second processors and a non-uniform memory architecture, and supporting virtual memory and a paging mechanism, said system comprising:

means for storing process code for the first processor in a first pageable memory region comprising a process heap segment;

means for expanding the process heap segment;

means for making a copy in virtual memory of said process code in a second pageable memory region; and

means for replacing the first memory region for the second processor with the second memory region at the same virtual address;

wherein said first and second memory regions have different latencies from the perspective of the second processor, and wherein a portion of the process heap segment is retained in the first memory region having the first paging characteristic.

44. A computer program product comprising instructions in machine readable form on a storage medium, said instructions when loaded into a computer system having at least first and second processors and a non-uniform memory architecture, and supporting virtual memory and a paging mechanism, operable to cause the system to perform the steps of:

storing process code for the first processor in a first pageable memory region comprising a process heap segment;

expanding the process heap segment;

making a copy in virtual memory of said process code in a second pageable memory region;

replacing the first memory for the second processor with the second memory region at the same virtual address;

wherein said first and second memory regions have different latencies from the perspective of the second processor, and wherein a portion of the process heap segment is retained in the first memory region having the first paging characteristic.