Mechanism for Live Migration of Virtual Machines with Memory Optimizations

• US 20110131568A1
• Filed: 11/30/2009
• Published: 06/02/2011
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Original Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Inventors: Heim, Itamar
• Granted Patent: US 8,327,060 B2
• Time in Patent Office: Days
• US Class Current: 718/1
• 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
• CPC Class Codes: G06F 9/4856 resumption being on a different machine, e.g. task migration, virtual machine migration G06F9/5088 takes precedence

Abstract

A mechanism for live migration of virtual machines (VMs) with memory optimizations is disclosed. A method of embodiments of the invention includes receiving a hash value for each of one or more memory pages of a migrating VM from a source host machine, obtaining a hash value for each of one or more memory pages hosted by a target host machine, and comparing the received hash values with the obtained hash values for matches. The method further comprises for each of the received hash values that do not match any of the obtained hash values, sending a negative acknowledgment to the source host machine for that hash value, and for each of the received hash values that do match any of the obtained hash values, using a memory page associated with the matching hash value at the target host machine for the migrating VM.

Claims

1. A computer-implemented method, comprising:

receiving, by a target host machine, a hash value for each of one or more memory pages of a migrating virtual machine (VM) from a source host machine;

obtaining, by the target host machine, a hash value for each of one or more memory pages hosted by the target host machine;

comparing, by the target host machine, the received hash values from the source host machine with the obtained hash values from the target host machine for matches;

for each of the received hash values from the source host machine that do not match any of the obtained hash values from the target host machine, sending, by the target host machine, a negative acknowledgment to the source host machine for that hash value; and

for each of the received hash values from the source host machine that do match any of the obtained hash values from the target host machine, using, by the target host machine, a memory page associated with the matching hash value at the target host machine for the migrating VM.

2. The method of claim 1, wherein the hash values for the one or more memory pages hosted by the target host machine are maintained by a memory sharing agent at the target host machine.

3. The method of claim 2, wherein the memory sharing agent includes a hash table data structure that stores the hash values for the one or more memory pages of the target host machine and a shared memory pages data module that stores data on which memory pages of the target host machine are shared between VMs hosted by the target host machine.

4. The method of claim 1, further comprising:

receiving, at the target host machine, an ordinal of a previously-sent memory page from the source host machine;

referencing, by the target host machine, a map correlating ordinals of memory pages received from the source host machine and memory pages of the migrating VM now on the target host machine to determine a memory page on the target host machine associated with the received ordinal; and

fetching, by the target host machine, the determined memory page from the migrating VM already at the target host machine.

5. The method of claim 4, wherein the ordinal of the previously-sent memory page is sent from the source host machine when the source host machine determines that a hash of another memory page of the migrating VM to be sent to the target host machine matches a hash of the memory page referenced by the ordinal.

6. The method of claim 5, wherein the ordinal of the previously-sent memory page is sent from the source host machine when the source host machine determines that a hash of another memory page of any of one or more other migrating VMs to be sent to the target host machine matches a hash of the memory page referenced by the ordinal.

7. The method of claim 1, wherein the one or more memory pages of the source host machine include memory pages of the source host machine that are shared between multiple VMs on the source host machine.

8. The method of claim 1, wherein the comparing the received hash values with the obtained hash values is terminated if more than a predetermined percentage of the received hashes sent to the target host machine do not match the obtained hash values.

9. A system, comprising:

a memory;

a processor communicably coupled to the memory; and

a memory sharing agent executed from the memory and the processor, the memory sharing agent configured to;

receive a hash value for each of one or more memory pages of a migrating virtual machine (VM) from a source host machine;

obtain a hash value for each of one or more memory pages managed by the memory sharing agent;

compare the received hash values from the source host machine with the obtained hash values from the memory sharing agent for matches;

for each of the received hash values from the source host machine that do not match any of the obtained hash values from the memory sharing agent, send a negative acknowledgment to the source host machine for that hash value; and

for each of the received hash values from the source host machine that do match any of the obtained hash values from the memory sharing agent, use a memory page associated with the matching hash value at a target host machine of the memory sharing agent for the migrating VM.

10. The system of claim 9, wherein the memory sharing agent includes a hash table data structure that stores the hash values for the one or more memory pages of the target host machine and a shared memory pages data module that stores data on which memory pages of the target host machine are shared between VMs hosted by the target host machine.

11. The system of claim 9, wherein the memory sharing agent further configured to:

receive an ordinal of a previously-sent memory page from the source host machine;

reference a map correlating ordinals of memory pages received from the source host machine and memory pages of the migrating VM now on the target host machine to determine a memory page on the target host machine associated with the received ordinal; and

fetch the determined memory page from the migrating VM already at the target host machine.

12. The system of claim 11, wherein the ordinal of the previously-sent memory page is sent from the source host machine when the source host machine determines that a hash of another memory page of the migrating VM to be sent to the target host machine matches a hash of the memory page referenced by the ordinal.

13. The system of claim 12, wherein the ordinal of the previously-sent memory page is sent from the source host machine when the source host machine determines that a hash of another memory page of any of one or more other migrating VMs to be sent to the target host machine matches a hash of the memory page referenced by the ordinal.

14. The system of claim 9, wherein the one or more memory pages of the source host machine include memory pages of the source host machine that are shared between multiple VMs on the source host machine.

15. The system of claim 9, wherein the comparing the received hash values with the obtained hash values is terminated if more than a predetermined percentage of the received hashes sent to the target host machine do not match the obtained hash values.

16. An article of manufacture comprising a machine-readable storage medium including data that, when accessed by a machine, cause the machine to perform operations comprising:

receiving a hash value for each of one or more memory pages of a migrating virtual machine (VM) from a source host machine;

obtaining a hash value for each of one or more memory pages hosted by a target host machine;

comparing the received hash values from the source host machine with the obtained hash values from the target host machine for matches;

for each of the received hash values from the source host machine that do not match any of the obtained hash values from the target host machine, sending a negative acknowledgment to the source host machine for that hash value; and

for each of the received hash values from the source host machine that do match any of the obtained hash values from the target host machine, using a memory page associated with the matching hash value at the target host machine for the migrating VM.

17. The article of manufacture of claim 16, wherein the hash values for the one or more memory pages hosted by the target host machine are maintained by a memory sharing agent at the target host machine.

18. The article of manufacture of claim 17, wherein the memory sharing agent includes a hash table data structure that stores the hash values for the one or more memory pages of the target host machine and a shared memory pages data module that stores data on which memory pages of the target host machine are shared between VMs hosted by the target host machine.

19. The article of manufacture of claim 16, wherein the machine-readable storage medium includes data that, when accessed by the machine, cause the machine to perform operations further comprising:

receiving an ordinal of a previously-sent memory page from the source host machine;

referencing a map correlating ordinals of memory pages received from the source host machine and memory pages of the migrating VM now on the target host machine to determine a memory page on the target host machine associated with the received ordinal; and

fetching the determined memory page from the migrating VM already at the target host machine.

20. The article of manufacture of claim 16, wherein the comparing the received hash values with the obtained hash values is terminated if more than a predetermined percentage of the received hashes sent to the target host machine do not match the obtained hash values.