Method for saving virtual machine state to a checkpoint file

摘要

A process for lazy checkpointing a virtual machine is enhanced to reduce the number of read/write accesses to the checkpoint file and thereby speed up the checkpointing process. The process for saving a state of a virtual machine running in a physical machine to a checkpoint file maintained in persistent storage includes the steps of copying contents of a block of memory pages, which may be compressed, into a staging buffer, determining after the copying if the buffer is full, and upon determining that the buffer is full, saving the buffer contents in a storage block of the checkpoint file.

主权项

1. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of saving a state of a virtual machine running in a physical machine to a checkpoint file that is maintained in persistent storage, the method comprising:
detecting an access to a memory page of the virtual machine; prior to the access, copying contents of a block of memory pages including the memory page into a buffer having a size that is at least two times greater than a size of the block; after said copying, determining if the buffer contains a predetermined number of blocks of memory pages of at least two; and upon determining that the buffer contains the predetermined number of blocks of memory pages, saving the contents of the blocks of memory pages in the buffer in a storage block of the checkpoint file.