COPY-ON-WRITE BY ORIGIN HOST IN VIRTUAL MACHINE LIVE MIGRATION

• US 20150242159A1
• Filed: 02/21/2014
• Published: 08/27/2015
• Est. Priority Date: 02/21/2014
• 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 9,851,918 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 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/5088 involving task migration

Abstract

Systems and methods for reducing network traffic in virtual machine live migration. An example method may comprise: intercepting, by a first computer system, a write access to a memory page by a virtual machine undergoing live migration from the first computer system to a second computer system; storing a copy of the memory page in a memory before allowing the virtual machine to modify the memory page; identifying data to be transmitted to the second computer system responsive to comparing the memory page and the copy of the memory page; and transmitting the data to the second computer system.

Claims

1. A method, comprising:

intercepting, by a first computer system, a write access to a memory page by a virtual machine undergoing live migration from the first computer system to a second computer system;

storing a copy of the memory page in a memory before allowing the virtual machine to modify the memory page;

identifying data to be transmitted to the second computer system responsive to comparing the memory page and the copy of the memory page; and

transmitting the data to the second computer system.

2. The method of claim 1, wherein intercepting the write access comprises write-protecting the memory page.

3. The method of claim 1, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that no data needs to be transmitted to the second computer system, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page does not exceed a first threshold value.

4. The method of claim 1, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises a difference between the memory page and the copy of the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a first threshold value.

5. The method of claim 1, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a second threshold value.

6. The method of claim 1, wherein storing the copy of the memory page further comprises:

ascertaining that an available memory is sufficient for storing the copy of the memory page.

7. The method of claim 1, wherein storing the copy of the memory page further comprises:

determining whether another copy of the memory page has been previously stored in the memory.

8. The method of claim 1, wherein storing the copy of the memory page further comprises:

compressing the memory page to produce a compressed copy of the memory page;

storing the compressed copy of the memory page in the memory.

9. The method of claim 8, wherein comparing the memory page and the copy of memory page further comprises performing one of:

compressing the memory page or uncompressing the copy of the memory page.

10. The method of claim 1, wherein storing a copy of the memory page further comprises:

storing one or more values of a hash function of one or more parts of the memory page.

11. The method of claim 10, wherein comparing the memory page and the copy of memory page further comprises:

calculating one or more values of the hash function of one or more parts of the memory page.

12. The method of claim 1, further comprising:

discarding the copy of the memory page.

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

a memory; and

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

intercept a write access to a memory page by a virtual machine undergoing live migration from the first computer system to a second computer system;

store copy of the memory page in a memory before allowing the virtual machine to modify the memory page;

identify data to be transmitted to the second computer system responsive to comparing the memory page and the copy of the memory page; and

transmit the data to the second computer system.

14. The system of claim 13, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that no data is to be transmitted to the second computer system, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page does not exceed a first threshold value.

15. The system of claim 13, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises a difference between the memory page and the copy of the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a first threshold value.

16. The system of claim 13, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a second threshold value.

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

intercept a write access to a memory page by a virtual machine undergoing live migration from the first computer system to a second computer system;

store a copy of the memory page in a memory before allowing the virtual machine to modify the memory page;

identify data to be transmitted to the second computer system responsive to comparing the memory page and the copy of the memory page; and

transmit the data to the second computer system.

18. The computer-readable non-transitory storage medium of claim 17, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that no data is to be transmitted to the second computer system, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page does not exceed a first threshold value.

19. The computer-readable non-transitory storage medium of claim 17, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises a difference between the memory page and the copy of the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a first threshold value.

20. The computer-readable non-transitory storage medium of claim 17, wherein identifying the data to be transmitted to the second computer system further comprises:

determining that the data comprises the memory page, responsive to ascertaining that a number of memory units which are different in the memory page and the copy of the memory page exceeds a second threshold value.