US 11,907,115 B2Granted

Indirect interface for virtual machine free page hinting

AssigneeRed Hat, Inc.

InventorMichael Tsirkin

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Abstract

A system includes a memory, a processor in communication with the memory, a hypervisor, and a guest OS. The guest OS is configured to store a plurality of hints in a list at a memory location. Each hint includes an address value and the memory location of the list is included in one of the respective address values associated with the plurality of hints. The guest OS is also configured to pass the list to the hypervisor. Each address value points to a respective memory page of a plurality of memory pages including a first memory page and a last memory page. The hypervisor is configured to free the first memory page pointed to by a first hint of the plurality of hints and free the last memory page pointed to by a second hint of the plurality of hints. Additionally, the last memory page includes the list.

Claims19

Dependent claims

A system comprising:

a memory;
a processor in communication with the memory;
a hypervisor;
and
a guest operating system (OS) configured to:
generate a list including a plurality of hints for a corresponding plurality of memory pages allocated to the guest OS, wherein an order in which each hint of the plurality of hints appears in the list indicates an order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages, wherein order of the hints of the plurality of hints is independent of an order of the memory pages of the corresponding plurality of memory pages in the memory, wherein the order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages indicates a first memory page and a last memory page and which indicates that the last memory page is not to be freed before the first memory page is freed, wherein each hint of the plurality of hints includes an address value associated with one memory page of the corresponding plurality of memory pages,
store the list in the last memory page, and
pass the list to the hypervisor, wherein the hypervisor is configured to:
free the first memory page according to the order in which each hint of the plurality of hints appears in the list, and
free the last memory page according to the order in which each hint of the plurality of hints appears in the list.

7 more elements

A method comprising:

generating, by a guest operating system (OS), a list including a plurality of hints for a corresponding plurality of memory pages allocated to the guest OS, wherein an order in which each hint of the plurality of hints appears in the list indicates an order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages, wherein the order of the hints of the plurality of hints is independent of an order of the memory pages of the corresponding plurality of memory pages in the memory, wherein the order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages indicates a first memory page and a last memory page and which indicates that the first memory page is to be freed before the last memory page is freed, wherein each hint of the plurality of hints includes an address value associated with one memory page of the corresponding plurality of memory pages;
storing, by the guest OS, the list in the last memory page;
passing, by the guest OS, the list to a hypervisor;
freeing, by the hypervisor, the first memory page according to the order in which each hint of the plurality of hints appears in the list;
and
freeing, by the hypervisor, the last memory page according to the order in which each hint of the plurality of hints appears in the list.

3 more elements

A method comprising:

generating, by a guest operating system (OS), a sequentially ordered list including a plurality of hints for a plurality of memory pages allocated to the guest OS, wherein an order in which each hint of the plurality of hints appears in the sequentially ordered list indicates an order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages, wherein the order in which the guest OS is permitted to free memory pages of the corresponding plurality of memory pages indicates a first memory page and a last memory page, wherein the guest OS is not permitted to free the last memory page before freeing the first memory page according to the order in which each hint of the plurality of hints appears in the sequentially ordered list, wherein a first hint associated with the first memory page appears in the sequentially ordered list before a last hint associated with the last memory page, wherein each hint of the plurality of hints includes address values associated with memory pages of the plurality of memory pages, wherein the last memory page is associated with an earlier address in the memory than the first memory page;
storing, by the guest OS, the sequentially ordered list in the last memory page;
passing, by the guest OS, a range of memory to a hypervisor, wherein the range of memory includes the last memory page;
and
freeing the first memory page according to the order in which each hint of the plurality of hints appears in the sequentially ordered list;
and
freeing the last memory page according to the order in which each hint of the plurality of hints appears in the sequentially ordered list.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/863,180Filed 30 Apr 2020
Published: US 2021/0342260 A14 Nov 2021
Granted: 20 Feb 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G06F 12/0253
Free address space management: garbage collection, i.e. reclamation of unreferenced memory
G06F 9/45558
Hypervisors; Virtual machine monitors: hypervisor-specific management and integration aspects
G06F 12/023
User address space allocation, e.g. contiguous or non contiguous base addressing: free address space management
G06F 12/1009
Address translation: using page tables, e.g. page table structures

Family

US 2021/0342260 A1Pre-grant publication · published 4 Nov 2021
US 11,907,115 B2This patent

From the US filing history. Foreign family members aren’t listed.

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