MANAGEMENT OF HOST PHYSICAL MEMORY ALLOCATION TO VIRTUAL MACHINES WITH A BALLOON APPLICATION

• US 20100241785A1
• Filed: 03/23/2010
• Published: 09/23/2010
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: RAO, Anil, CHEN, Xiaoxin, WALDSPURGER, Carl A.
• Granted Patent: US 8,359,451 B2
• Time in Patent Office: Days
• 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

Methods and systems for managing distribution of host physical memory (HPM) among virtual machines (VMs) executing on a host via a hypervisor are presented, where each VM has guest system software including an operating system. A method includes an operation for reserving, by a balloon application executing in a first VM, a guest virtual memory (GVM) location in the first VM. The GVM location is mapped to a guest physical memory (GPM) location, which is mapped to a host physical memory (HPM) location. The balloon application is responsive to the hypervisor for reserving memory. Further, the method includes operations for writing a value to the reserved GVM location and for remapping a plurality of GPM locations containing the value to a single HPM location. The remapping is performed by a content-based page sharing component of the hypervisor. Additionally, the method reclaims the HPM location when the HPM location is freed due to the remapping, and assigns the reclaimed HPM location to a different VM or to a pool of available HPM locations.

Claims

1. A method for managing distribution of host physical memory (HPM) among virtual machines (VMs) executing on a host via a hypervisor, each VM having guest system software including an operating system, the method comprising:

reserving, by a balloon application executing in a first VM, a guest virtual memory (GVM) location in the first VM, the GVM location being mapped to a guest physical memory (GPM) location, which is mapped to a host physical memory (HPM) location, the balloon application being responsive to the hypervisor for reserving memory;

writing a value to the reserved GVM location;

remapping a plurality of GPM locations containing the value to a single HPM location using a content-based page sharing component of the hypervisor;

reclaiming the HPM location when the HPM location is freed due to the remapping; and

assigning the reclaimed HPM location to a pool of available HPM locations.

2. The method as recited in claim 1, wherein a size of the GVM location, the GPM location, and the HPM location is one page of memory, wherein writing the value to the GVM location includes filling a page of memory corresponding to the GMV location with a pattern.

3. The method as recited in claim 2, wherein writing the value further includes filling the page of memory with all zeros.

4. The method as recited in claim 1, further including:

marking the GPM location as read only by the hypervisor; and

trapping a write to the GPM location to detect that the GPM location is no longer owned by the balloon application.

5. The method as recited in claim 4, further including:

mapping the GPM location to an available HPM location; and

proceeding with the write to the GPM location.

6. The method as recited in claim 1, wherein remapping a plurality of GPM locations further includes:

setting corresponding page table entries for the GPM locations to invalid.

7. The method as recited in claim 1, further including:

sending a request from the hypervisor to the balloon application before reserving the GVM location.

8. The method as recited in claim 1, further including:

performing, by the balloon application, a memory read operation to the GVM location that causes the GVM location to be mapped to the GPM location.

9. A method for managing distribution of host physical memory (HPM) among virtual machines (VMs) executing on a host via a hypervisor, each VM having guest system software including an operating system, the method comprising:

receiving, by a balloon application executing in a first VM, a memory allocation request from the hypervisor;

reserving a guest virtual memory (GVM) location in response to the memory allocation request, the GVM location being mapped to a guest physical memory (GPM) location, which is mapped to a host physical memory (HPM) location;

sending the GVM location to the hypervisor;

remapping the GPM location mapped by the GVM location;

reclaiming the HPM location after remapping the GPM location; and

assigning the reclaimed HPM location to a second VM.

10. The method as recited in claim 9, wherein remapping the GPM location further includes:

mapping the GPM location to a new HPM location, wherein the new HPM location can be shared by multiple GPM locations.

11. The method as recited in claim 9, wherein remapping the GPM location further includes:

unmapping the GPM location, wherein a page table entry for the GPM location includes an invalid mapping.

12. The method as recited in claim 9, wherein a size of the GVM location, the GPM location, and the HPM location is one page of memory.

13. The method as recited in claim 9, further including:

marking the GPM location as read only by the hypervisor; and

trapping a write to the GPM location to detect that the GPM location is no longer owned by the balloon application.

14. The method as recited in claim 13, further including:

mapping the GPM location to an available HPM location; and

proceeding with the write to the GPM location.

15. A system for managing distribution of physical memory among virtual machines (VMs) executing on a host via a hypervisor, each VM having guest system software including an operating system, the system comprising:

a balloon application executing in a first VM, the balloon application defined to reserve a guest virtual memory (GVM) location in the first VM, the GVM location being mapped to a guest physical memory (GPM) location, which is mapped to a host physical memory (HPM) location, the balloon application being responsive to the hypervisor for reserving memory; and

a content-based page sharing component in the hypervisor that remaps a plurality of GPM locations to a single HPM location when the balloon application writes a value to the reserved GVM location and each page from the plurality of GPM locations contains the value;

wherein the hypervisor reclaims the HPM location when the HPM location is freed due to being remapped in order to make the HPM location available to a pool of available HPM locations.

16. The system as recited in claim 15, wherein a size of the GVM location, the GPM location, and the HPM location is one page of memory, wherein writing the value to the GVM location includes filling a page of memory corresponding to the GMV location with a pattern.

17. The system as recited in claim 15, wherein the hypervisor marks the GPM location as read only, wherein the hypervisor traps any write to the GPM location to detect that the GPM location is no longer owned by the balloon application.

18. The system as recited in claim 15, wherein the hypervisor unmapps the GPM location by writing a page table entry for the GPM location with an invalid mapping.

19. The system as recited in claim 15, wherein the balloon application performs a memory read operation to the GVM location to cause the GVM location to be mapped to the GPM location.