Vmware, Inc.

Irene Zhang

Alexander T Garthwaite

Yury Baskakov

Rajesh Venkatasubramanian

Kiran Tati

Jesse Pool

Kevin Scott Christopher

Seongbeom Kim

Nikhil Bhatia

Memory performance in a computer system that implements large page mapping is improved even when memory is scarce by identifying page sharing opportunities within the large pages at the granularity of small pages and breaking up the large pages so that small pages within the large page can be freed up through page sharing. In addition, the number of small page sharing opportunities within the large pages can be used to estimate the total amount of memory that could be reclaimed through page sharing.

Identification of page sharing opportunities within large pages

A process for lazy checkpointing is enhanced to reduce the number of read/write accesses to the checkpoint file and thereby speed up the checkpointing process. The process for restoring a state of a virtual machine (VM) running in a physical machine from a checkpoint file that is maintained in persistent storage includes the steps of detecting access to a memory page of the virtual machine that has not been read into physical memory of the VM from the checkpoint file, determining a storage block of the checkpoint file to which the accessed memory page maps, writing contents of the storage block in a buffer, and copying contents of a block of memory pages that includes the accessed memory page from the buffer to corresponding locations of the memory pages in the physical memory of the VM. The storage block of the checkpoint file may be compressed or uncompressed.

Method for restoring virtual machine state from a checkpoint file

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.

Method for saving virtual machine state to a checkpoint file

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Irene Zhang