Method and system for restoring consumed memory after memory consolidation

A method for reducing latency associated with accessing content of a memory page that has been dropped out of a buffer cache of a guest operating system of a virtual machine in response to a ballooning process, comprising:

• detecting an I/O read command from the guest operating system for a full-sized page stored on a virtual disk of the virtual machine;
• recording a location of the page as stored on the virtual disk;
• determining that the guest operating system is writing to the page and recording data regarding the page;
• prefetching contents of the page from the recorded location on the virtual disk;
• detecting that a guest operating system attempts to read at the recorded location;
• and
• providing the prefetched content of the page to the guest operating system.

A non-transitory computer readable storage medium storing instructions which when executed by a processor cause the processor to perform a method for reducing latency associated with accessing content of a memory page that has been swapped out by a guest operating system in a virtualized computer system, the method comprising:

• identifying content previously swapped out by the guest operating system;
• prefetching the identified content from the guest operating system's swap file;
• caching the prefetched content in a prefetch cache in host machine memory;
• detecting an I/O read command which is associated with the cached content and issued by the guest operating system;
• and
• providing the cached content from the prefetch cache, thereby avoiding accessing the guest operating system's swap file.

A non-transitory computer readable storage medium storing instructions which when executed by a processor cause the processor to perform a method for reducing latency associated with accessing content of a memory page that has been dropped out of a guest operating system's buffer cache in response to a ballooning process, the method comprising:

• detecting an I/O read command from within the virtual machine for a full-sized page stored on a virtual disk of the virtual machine;
• recording a location of the page as stored on the virtual disk;
• determining that a guest operating system is writing to the page and recording data regarding the page;
• prefetching content of the page from the recorded location on the virtual disk;
• detecting that a guest operating system attempts to read at the recorded location;
• and
• providing the prefetched content of the page to the guest operating system.