System and method improving memory usage in virtual machines by releasing additional memory at the cost of increased CPU overhead

An apparatus, comprising:

• at least one processor executing a method for managing memory among a plurality of concurrently-running virtual machines;
• and
• a non-transitory memory device that stores a set of computer readable instructions for implementing and executing said memory management method, wherein said method comprises:
• providing at least one memory optimization mechanism, as executed by at least one processor on at least one computer, which can reduce a memory usage of a virtual machine at a cost of increasing a central processing unit (CPU) usage;
• periodically collecting information on a memory usage and a CPU usage of each virtual machine;
• in response to a first virtual machine exhibiting a high level of memory use, identifying at least one second virtual machine with an extra CPU capacity;
• applying, to the at least one second virtual machine the at least one memory optimization mechanism, to reduce memory used by the at least one second virtual machine, thereby providing a portion of freed memory;
• and
• allocating the portion of freed memory to the first virtual machine, wherein the plurality of virtual machines includes a plurality of virtual machines distinct from the first virtual machine each with an extra CPU capacity, the method further comprising:
• identifying the at least one second virtual machine with an extra CPU capacity by giving preference to virtual machines with one of higher extra CPU capacities and higher memory usage.

An apparatus comprising:

• at least one processor;
• and
• a non-transitory memory device, said memory device storing instructions for a method of controlling a memory allocation among a plurality of concurrently-running virtual machines (VMs), said method comprising:
• providing a plurality of memory optimization mechanisms, each of which can reduce a memory usage of a virtual machine at a cost of increasing a central processing unit (CPU) usage, wherein each memory optimization mechanism would be selectively executed by a processor on a computer executing a virtual machine;
• monitoring a central processing unit (CPU) usage and a memory usage of each said VM, as executed by at least one processor on at least one computer,
• detecting that a first VM of the plurality of concurrently-running VMs requires more memory;
• and
• exercising a memory allocation mechanism for allocating additional memory to the first VM;
• and
• allocating the additional memory to the first VM, wherein the additional memory to be allocated is determined based upon considering a cost of increasing a central processing unit (CPU) usage of the concurrently-running VMs in order to reallocate memory to said first VM,
• wherein the memory allocation mechanism for allocating additional memory comprises:
• determining initially if any free memory not currently used by any of the other VMs of said plurality of VMs is available, and, if so, allocating at least a portion of said free memory to said first VM, the additional memory thereby being allocated to said first VM at no additional increase of CPU usage of any of said concurrently-running VMs;
• and
• if no free memory is currently available, determining whether any of the other VMs of said plurality of VMs can free up memory if one or more memory optimization mechanisms were to be applied by identifying at least one memory optimization mechanism from the plurality of memory optimization mechanisms, to apply to at least one of the other VMs, by giving preference to memory optimizations which at least one of free up more memory and consume fewer CPU cycles, and, if so, allocating said freed up memory to said first VM.