REDUCING REDUNDANT NETWORK TRANSMISSIONS IN VIRTUAL MACHINE LIVE MIGRATION

• US 20150212846A1
• Filed: 01/29/2014
• Published: 07/30/2015
• Est. Priority Date: 01/29/2014
• Status: Active Grant

• Current Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Original Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Inventors: Tsirkin, Michael
• Granted Patent: US 9,672,056 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 2009/45583 Memory management, e.g. access or allocation
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

Systems and methods for reducing redundant network transmissions in virtual machine live migration. An example method may comprise: reading, by a hypervisor running on a first computer system, from a memory mapped into an address space of a virtual machine undergoing live migration from the first computer system to a second computer system, a data structure comprising a plurality of records, each record mapping an address of a memory page to an identifier of a virtual disk frame storing contents of the memory page; reading a plurality of page modification flags, each page modification flag indicating that contents of a corresponding memory page differ from contents of a virtual disk frame referenced by the data structure; responsive to determining that a memory page is referenced by the data structure and that a page modification flag corresponding to the memory page is set, transmitting the memory page to the second computer system; and responsive to determining that a memory page is not referenced by the data structure, transmitting the memory page to the second computer system.

Claims

1. A method, comprising:

reading, by a hypervisor running on a first computer system, from a memory mapped into an address space of a virtual machine undergoing live migration from the first computer system to a second computer system, a data structure comprising a plurality of records, each record mapping an address of a memory page to an identifier of a virtual disk frame storing contents of the memory page;

reading, from the memory mapped into the address space of the virtual machine, a plurality of page modification flags, each page modification flag indicating that contents of a corresponding memory page differ from contents of a virtual disk frame referenced by the data structure;

responsive to determining that a memory page is referenced by the data structure and that a page modification flag corresponding to the memory page is set, transmitting the memory page to the second computer system; and

responsive to determining that a memory page is not referenced by the data structure, transmitting the memory page to the second computer system.

2. The method of claim 1, further comprising:

responsive to determining that the memory page is referenced by the data structure and that the page modification flag corresponding to a memory page is clear, notifying the second computer system of the address of the memory page.

3. The method of claim 1, wherein the determining comprises cycling through a subset of memory pages mapped into the address space of the virtual machine.

4. The method of claim 1, wherein the data structure is provided by two or more data structures.

5. The method of claim 1, wherein the identifier of the virtual disk frame comprises an offset of the frame on the virtual disk.

6. The method of claim 5, wherein the identifier of the virtual disk frame further comprises an identifier of the virtual disk.

7. The method of claim 5, wherein the virtual disk resides on one of:

a network attached storage (NAS) system or a storage area network (SAN) system.

8. A system of a first computer system, comprising:

a memory; and

one or more processors, coupled to the memory, to;

read, by a hypervisor running on the first computer system, from a memory mapped into an address space of a virtual machine undergoing live migration from the first computer system to a second computer system, a data structure comprising a plurality of records, each record mapping an address of a memory page to an identifier of a virtual disk frame storing contents of the memory page;

read, from the memory mapped into the address space of the virtual machine, a plurality of page modification flags, each page modification flag indicating that contents of a corresponding memory page differ from contents of a virtual disk frame referenced by the data structure;

responsive to determining that a memory page is referenced by the data structure and that a page modification flag corresponding to the memory page is set, transmit the memory page to the second computer system; and

responsive to determining that a memory page is not referenced by the data structure, transmit the memory page to the second computer system.

9. The system of claim 8, wherein the processors are further to:

responsive to determining that the memory page is referenced by the data structure and that the page modification flag corresponding to a memory page is clear, notify the second computer system of the address of the memory page.

10. The system of claim 8, wherein the determining comprises cycling through a subset of memory pages mapped into the address space of the virtual machine.

11. The system of claim 8, wherein the data structure is provided by two or more data structures.

12. The system of claim 8, wherein the identifier of the virtual disk frame comprises an offset of the frame on the virtual disk.

13. The system of claim 12, wherein the identifier of the virtual disk frame further comprises an identifier of the virtual disk.

14. The system of claim 12, wherein the virtual disk resides on one of:

a network attached storage (NAS) system or a storage area network (SAN) system.

15. A computer-readable non-transitory storage medium comprising executable instructions that, when executed by a first computer system, cause the first computer system to:

read, by a hypervisor running on the first computer system, from a memory mapped into an address space of a virtual machine undergoing live migration from the first computer system to a second computer system, a data structure comprising a plurality of records, each record mapping an address of a memory page to an identifier of a virtual disk frame storing contents of the memory page;

read, from the memory mapped into the address space of the virtual machine, a plurality of page modification flags, each page modification flag indicating that contents of a corresponding memory page differ from contents of a virtual disk frame referenced by the data structure;

responsive to determining that a memory page is referenced by the data structure and that a page modification flag corresponding to the memory page is set, transmit the memory page to the second computer system; and

responsive to determining that a memory page is not referenced by the data structure, transmit the memory page to the second computer system.

16. The computer-readable non-transitory storage medium of claim 15, further comprising executable instructions causing the first computer system to:

responsive to determining that the memory page is referenced by the data structure and that the page modification flag corresponding to a memory page is clear, notify the second computer system of the address of the memory page.

17. The computer-readable non-transitory storage medium of claim 15, wherein the determining comprises cycling through a subset of memory pages mapped into the address space of the virtual machine.

18. The computer-readable non-transitory storage medium of claim 15, wherein the data structure is provided by two or more data structures.

19. The computer-readable non-transitory storage medium of claim 15, wherein the identifier of the virtual disk frame comprises an offset of the frame on the virtual disk.

20. The computer-readable non-transitory storage medium of claim 19, wherein the virtual disk resides on one of:

a network attached storage (NAS) system or a storage area network (SAN) system.