External disk cache for guest operating system in a virtualized environment

A system for executing a plurality of virtual machines (VMs), the system comprising:

• a host physical memory;
• and
• a hardware processor configured to:
• execute, in a first virtual machine (VM) comprising a guest block device driver and a memory-mapped virtual storage device, wherein the guest device driver is configured to provide an interface to the memory-mapped virtual storage device;
• maintain a disk cache associated with the virtual storage device, wherein the disk cache resides in the host physical memory outside of portions of the host physical memory associated with guest physical memory of the first VM;
• and
• responsive to determining that available host physical memory satisfies a threshold condition, reclaim a target portion of the host physical memory allocated to the disk cache.

A non-transitory computer readable medium comprising computer executable instructions for managing computing resources of a physical server executing a plurality of virtual machines (VMs), including instructions for:

• executing, in a first virtual machine (VM) of the plurality of VMs, a guest block device driver configured to provide an interface to a memory-mapped virtual storage device;
• maintaining, by a virtual machine monitor, a disk cache associated with the virtual storage device, wherein the disk cache resides in a host physical memory of the physical server outside of portions of the host physical memory associated with guest physical memory of the first VM;
• and
• responsive to determining that available host physical memory satisfies a threshold condition, reclaiming a target portion of the host physical memory allocated to the disk cache.