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US 10,768,965 B1Granted
Reducing copy operations for a virtual machine migration
AssigneeAmazon Technologies, Inc.
InventorsAdi Habusha, Ali Ghassan Saidi
Life of this patent
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Abstract
Systems and methods are provided to reduce the number of redundant copy operations performed as part of a live migration of a virtual machine executing a guest. A hypervisor can queue the copy operations in a processing engine. While pre-copying for the live migration of the VM, the guest may continue to write to the pages. In one embodiment, the processing engine may clear a dirty page just before performing the copy operation of the modified page to a target device, thus extending the window of time to capture any future writes to that page.
Claims20
A system comprising:
- a host processor configured to execute a hypervisor, wherein the hypervisor is configured to:
- provide information, associated with a page table entry (PTE) corresponding to a page of memory, to schedule a copy operation of the page for a live migration of a virtual machine (VM) running on the host processor, wherein the page is associated with a guest operating system (OS) executing within the VM, and wherein the PTE comprises a dirty page indicator to indicate that the page has been modified;
- and
- a processing engine separate from the hypervisor executing on the host processor, the processing engine configured to:
- receive the information associated with the PTE corresponding to the page, the information including an address of the PTE associated with the guest OS;
- read the dirty page indicator in the PTE using the address to determine that the page has been modified;
- schedule the page for the copy operation;
- determine that the page has later been modified again;
- execute an atomic operation to clear the dirty page indicator in the PTE after the later modification and before performing the copy operation;
- and
- perform the copy operation.
8 more elements
A method, comprising:
- receiving, by a processing engine separate from a hypervisor executing on a host processor, an address of a page table entry (PTE) in memory corresponding to a page associated with a guest, the address being received from the hypervisor to perform a copy operation subsequent to modification of the page by the guest, the hypervisor executing on the host processor in a host device, wherein the guest is executing within a virtual machine (VM) running on the host processor, the PTE comprising a dirty page indicator to indicate that the page has been modified;
- determining that the page has been modified;
- scheduling the page for the copy operation;
- determining that the page has later been modified again;
- executing, by the processing engine, an atomic operation to clear the dirty page indicator in the PTE after the later modification and before performing the copy operation;
- and
- performing, by the processing engine, the copy operation.
4 more elements
An apparatus comprising:
- a memory configured to store information associated with a copy operation to be performed for a page, wherein the information is received from a hypervisor executing on a host processor, and wherein the page is associated with a guest executing within a virtual machine (VM) executing on the host processor;
- a processor separate from the hypervisor executing on the host processor, the processor configured to:
- determine that the page has been modified;
- schedule the page for the copy operation;
- determine that the page has later been modified again;
- and
- clear a dirty page indicator in a page table entry (PTE) corresponding to the page using the information after the later modification and prior to performing the copy operation;
- and
- a direct memory access (DMA) controller configured to perform the copy operation.
6 more elements
Dependencies are inferred from the claim text.