Determining memory conditions in a virtual machine

• US 7,702,843 B1
• Filed: 09/21/2006
• Issued: 04/20/2010
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: Chen, Xiaoxin, Waldspurger, Carl, Rao, Anil
• Primary Examiner(s): Tsai; Sheng-Jen
• Assistant Examiner(s): Dudek; Edward J
• Application Number:
  US11/525,561
• Time in Patent Office: 1,307 Days
• Field of Search: 711/6, 707/206, 718/1
• US Class Current: 711/6
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence
• CPC Class Codes: G06F 12/109 for multiple virtual address spaces, e.g. segmentation G06F12/1036 takes precedence
• CPC Class Codes: G06F 2009/45583 Memory management, e.g. access or allocation
• CPC Class Codes: G06F 2209/508 Monitor
• CPC Class Codes: G06F 2212/151 Emulated environment, e.g. virtual machine
• CPC Class Codes: G06F 9/45545 Guest-host, i.e. hypervisor is an application program itself, e.g. VirtualBox
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/5016 the resource being the memory
• CPC Class Codes: G06F 9/5077 Logical partitioning of resources; Management or configuration of virtualized resources specific details on emulation or internal functioning of virtual machines G06F9/455

Abstract

Memory assigned to a virtual machine is reclaimed. A resource reservation application running as a guest application on the virtual machine reserves a location in guest virtual memory. The corresponding physical memory can be reclaimed and allocated to another virtual machine. The resource reservation application allows detection of guest virtual memory page-out by the guest operating system. Measuring guest virtual memory page-out is useful for determining memory conditions inside the guest operating system. Given determined memory conditions, memory allocation and reclaiming can be used control memory conditions. Memory conditions in the virtual machine can be controlled with the objective of achieving some target memory conditions.

Claims

1. A method for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the method comprising:

executing a first application on the virtual machine, said first application reserving a first location of a first size in the guest virtual memory;

performing with a first frequency a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

determining if said first location is not mapped to said second location;

measuring an interval between performing said first predetermined action and determining that said first location in the guest virtual memory is not mapped to said second location in the guest physical memory;

responsive to said interval, determining a memory condition in the virtual machine; and

responsive to said determined memory condition in the virtual machine, modifying said first frequency with which said first predetermined action is performed.

2. The method of claim 1, wherein performing said first predetermined action comprises accessing said first location in the guest virtual memory.

3. The method of claim 1, wherein said first location in the guest virtual memory is described by a page table entry comprising an access bit indicating if a page associated with the page table entry has been accessed, and wherein performing said first predetermined action comprises modifying said access bit of said page table entry.

4. The method of claim 1, further comprising the step of:

responsive to said determined memory condition in the virtual machine, reserving a third location of a second size in the guest virtual memory.

5. The method of claim 1, further comprising the step of:

responsive to said determined memory condition in the virtual machine, reclaiming a third location in physical memory allocated to the virtual machine.

6. The method of claim 5, wherein a fourth location in the guest physical memory is mapped to the third location in physical memory, and wherein reclaiming the third location in physical memory comprises paging-out said fourth location in the guest physical memory.

7. The method of claim 5, wherein reclaiming the third location in physical memory comprises reserving a fourth location in the guest physical memory, wherein said fourth location in the guest physical memory is mapped to the third location in physical memory.

8. The method of claim 7, wherein said fourth location in the guest physical memory is reserved by said first application.

9. The method of claim 7, wherein said fourth location in the guest physical memory is reserved by a device driver executing on the virtual machine.

10. The method of claim 1, further comprising the step of:

executing a third application on the virtual machine, said third application reserving a third location of a second size in the guest virtual memory.

11. The method of claim 10, wherein said second size is different than said first size.

12. The method of claim 10, further comprising the step of:

performing with a second frequency a second predetermined action, wherein performing said second predetermined action causes said third location in the guest virtual memory to be mapped to a fourth location in the guest physical memory.

13. A method for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the method comprising:

executing a first application on the virtual machine, said first application reserving a first location of a first size in the guest virtual memory;

performing with a first frequency a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

determining if said first location is not mapped to said second location;

measuring an interval between performing said first predetermined action and determining that said first location in the guest virtual memory is not mapped to said second location in the guest physical memory;

responsive to said interval, determining a memory condition in the virtual machine; and

sending said determined memory condition to said first application.

14. A method for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the method comprising:

executing a first application on the virtual machine, said first application reserving a first location of a first size in the guest virtual memory;

performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

checking by a second application running outside the virtual machine if said first location is mapped to said second location;

measuring an interval between performing said first predetermined action and the checking;

responsive to said interval and said checking, determining by the second application a memory condition in the virtual machine; and

sending said determined memory condition to a third application executing on the virtual machine.

15. A method for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the method comprising:

executing a first application on the virtual machine, said first application reserving a first location of a first size in the guest virtual memory;

performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

checking by a second application running outside the virtual machine if said first location is mapped to said second location;

measuring an interval between performing said first predetermined action and the checking;

responsive to said interval and said checking, determining by the second application a memory condition in the virtual machine;

executing a third application on the virtual machine, said third application reserving a third location of a second size in the guest virtual memory; and

performing with a second frequency a second predetermined action, wherein performing said second predetermined action causes said third location in the guest virtual memory to be mapped to a fourth location in the guest physical memory;

wherein said second frequency is different than said first frequency.

16. A computer program product for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the computer program product comprising a computer readable medium, the computer readable medium comprising:

computer code for executing a first application on the virtual machine, said first application comprises computer code for reserving a first location of a first size in the guest virtual memory;

computer code for performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

computer code for checking by a second application running outside the virtual machine if said first location is mapped to said second location;

computer code for measuring an interval between performing said first predetermined action and the checking; and

computer code, responsive to said interval and said checking, for determining by the second application a memory condition in the virtual machine;

computer code, responsive to said determined memory condition in the virtual machine, for modifying said first frequency with which said first predetermined action is performed.

17. The computer program product of claim 16, wherein said computer code for performing said first predetermined action comprises computer code for accessing said first location in the guest virtual memory.

18. The computer program product of claim 16, wherein said first location in the guest virtual memory is described by a page table entry comprising an access bit indicating if a page associated with the page table entry has been accessed, and wherein said computer code for performing said first predetermined action comprises computer code for modifying said access bit of said page table entry.

19. The computer program product of claim 16, the computer readable medium further comprising:

computer code, responsive to said determined memory condition in the virtual machine, for reserving a third location of a second size in the guest virtual memory.

20. The computer program product of claim 16, the computer readable medium further comprising:

computer code, responsive to said determined memory condition in the virtual machine, for reclaiming a third location in physical memory allocated to the virtual machine.

21. The computer program product of claim 20, wherein a fourth location in the guest physical memory is mapped to the third location in physical memory, and wherein said computer code for reclaiming the third location in physical memory comprises computer code for paging-out said fourth location in the guest physical memory.

22. The computer program product of claim 20, wherein said computer code for reclaiming the third location in physical memory comprises computer code for reserving a fourth location in the guest physical memory, wherein said fourth location in the guest physical memory is mapped to the third location in physical memory.

23. The computer program product of claim 16, the computer readable medium further comprising:

computer code for executing a third application on the virtual machine, said third application comprising computer code for reserving a third location of a second size in the guest virtual memory.

24. The computer program product of claim 23, wherein said second size is different than said first size.

25. The computer program product of claim 23, the computer readable medium further comprising:

computer code for performing with a second frequency a second predetermined action, wherein performing said second predetermined action causes said third location in the guest virtual memory to be mapped to a fourth location in the guest physical memory.

26. A computer program product for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the computer program product comprising a computer readable medium, the computer readable medium comprising:

computer code for executing a first application on the virtual machine, said first application comprises computer code for reserving a first location of a first size in the guest virtual memory;

computer code for performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

computer code for checking by a second application running outside the virtual machine if said first location is mapped to said second location;

computer code for measuring an interval between performing said first predetermined action and the checking;

computer code, responsive to said interval and said checking, for determining by the second application a memory condition in the virtual machine; and

computer code for sending said determined memory condition to said first application.

27. A computer program product for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the computer program product comprising a computer readable medium, the computer readable medium comprising:

computer code for executing a first application on the virtual machine, said first application comprises computer code for reserving a first location of a first size in the guest virtual memory;

computer code for performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

computer code for checking by a second application running outside the virtual machine if said first location is mapped to said second location;

computer code for measuring an interval between performing said first predetermined action and the checking;

computer code, responsive to said interval and said checking, for determining by the second application a memory condition in the virtual machine; and

computer code for sending said determined memory condition to a third application executing on the virtual machine.

28. A computer program product for determining memory conditions in a virtual machine, said virtual machine comprising guest virtual memory and guest physical memory, the computer program product comprising a computer readable medium, the computer readable medium comprising:

computer code for executing a first application on the virtual machine, said first application comprises computer code for reserving a first location of a first size in the guest virtual memory;

computer code for performing, by the first application and with a first frequency, a first predetermined action, wherein performing said first predetermined action causes said first location in the guest virtual memory to be mapped to a second location in the guest physical memory;

computer code for checking by a second application running outside the virtual machine if said first location is mapped to said second location;

computer code for measuring an interval between performing said first predetermined action and the checking;

computer code, responsive to said interval and said checking, for determining by the second application a memory condition in the virtual machine;

computer code for executing a third application on the virtual machine, said third application comprising computer code for reserving a third location of a second size in the guest virtual memory; and

computer code for performing with a second frequency a second predetermined action, wherein performing said second predetermined action causes said third location in the guest virtual memory to be mapped to a fourth location in the guest physical memory;

wherein said second frequency is different than said first frequency.