Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM' s memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: Memory assigned to a virtual machine is reclaimed. A resource reservation application running as a guest application on the virtual machine reserves a location in guest virtual memory. The corresponding physical memory can be reclaimed and allocated to another virtual machine. The resource reservation application allows detection of guest virtual memory page-out by the guest operating system. Measuring guest virtual memory page-out is useful for determining memory conditions inside the guest operating system. Given determined memory conditions, memory allocation and reclaiming can be used control memory conditions. Memory conditions in the virtual machine can be controlled with the objective of achieving some target memory conditions.

Abstract: A method and system for providing quality of service to a plurality of hosts accessing a common resource is described. According to one embodiment, a plurality of IO requests is received from clients executing as software entities on one of the hosts. An IO request queue for each client is separately managed, and an issue queue is populated based on contents of the IO request queues. When a host issue queue is not full, a new IO request is entered into the host issue queue and is issued to the common resource. A current average latency observed at the host is calculated, and an adjusted window size is calculated at least in part based on the current average latency. The window size of the issue queue is adjusted according to the calculated window size.

Abstract: A thread scheduling mechanism is provided that flexibly enforces performance isolation of multiple threads to alleviate the effect of anti-cooperative execution behavior with respect to a shared resource, for example, hoarding a cache or pipeline, using the hardware capabilities of simultaneous multi-threaded (SMT) or multi-core processors. Given a plurality of threads running on at least two processors in at least one functional processor group, the occurrence of a rescheduling condition indicating anti-cooperative execution behavior is sensed, and, if present, at least one of the threads is rescheduled such that the first and second threads no longer execute in the same functional processor group at the same time.

Abstract: Memory assigned to a virtual machine is reclaimed. A resource reservation application running as a guest application on the virtual machine reserves a location in guest virtual memory. The corresponding physical memory can be reclaimed and allocated to another virtual machine. The resource reservation application allows detection of guest virtual memory page-out by the guest operating system. Measuring guest virtual memory page-out is useful for determining memory conditions inside the guest operating system. Given determined memory conditions, memory allocation and reclaiming can be used control memory conditions. Memory conditions in the virtual machine can be controlled with the objective of achieving some target memory conditions.

Abstract: Methods, computer programs, and systems for managing thread performance in a computing environment based on cache occupancy are provided. In one embodiment, a computer implemented method assigns a thread performance counter to threads being created to measure the number of cache misses for the threads. The thread performance counter is deduced in one embodiment based on performance counters associated with each core in a processor. The method further calculates a self-thread value as the change in the thread performance counter of a given thread during a predetermined period, and an other-thread value as the sum of all the changes in the thread performance counters for all threads except for the given thread. Further, the method estimates a cache occupancy for the given thread based on a previous occupancy for the given thread, and the calculated shelf-thread and other-thread values. The estimated cache occupancy is used to assign computing environment resources to the given thread.

Abstract: A swap space is provided for a host computer system, where the swap space includes a plurality of swap files with each individual swap file for swapping data only for a single corresponding virtual machine (VM). The per-VM swap space is used solely by the single, corresponding VM, such that only that particular VM's memory is allowed to be swapped out to the swap file.

Abstract: A system and related method of operation for migrating the memory of a virtual machine from one NUMA node to another. Once the VM is migrated to a new node, migration of memory pages is performed while giving priority to the most utilized pages, so that access to these pages becomes local as soon as possible. Various heuristics are described to enable different implementations for different situations or scenarios.

Abstract: A swap space is provided for a host computer system, where the swap space includes a plurality of swap files with each individual swap file for swapping data only for a single corresponding virtual machine (VM). The per-VM swap space is used solely by the single, corresponding VM, such that only that particular VM's memory is allowed to be swapped out to the swap file.

Abstract: A computer system has one or more software contexts that share use of a memory that is divided into units such as pages. In the preferred embodiment of the invention, the contexts are, or include, virtual machines running on a common hardware platform. The contents, as opposed to merely the addresses or page numbers, of virtual memory pages that are accessible to one or more contexts are examined. If two or more context pages are identical, then their memory mappings are changed to point to a single, shared copy of the page in the hardware memory, thereby freeing the memory space taken up by the redundant copies. The shared copy is then preferably marked copy-on-write. Sharing is preferably dynamic, whereby the presence of redundant copies of pages is preferably determined by hashing page contents and performing full content comparisons only when two or more pages hash to the same key.

Abstract: In a method of utilizing cache metadata to optimize memory access, cache metadata associated with a set of cache locations is inspected by software. The cache metadata is analyzed to determine memory utilization. Memory access is optimized based on results of the analysis of the cache metadata.

Abstract: A method and system of managing data access in a shared memory cache of a processor are disclosed. The method includes probing one or more memory addresses that map to a subset of the shared memory cache and sensing a plurality of events in the one or more memory addresses. Cache utilization information is then obtained by reading a hardware performance counter of the processor. The hardware performance counter is incremented based on the occurrence of the plurality of events. Based upon the cache utilization information, an occurrence of one of the plurality of events is reduced.

Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM's memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: A virtual-machine-based system provides a mechanism to implement application file I/O operations of protected data by implementing the I/O operations semantics in a shim layer with memory-mapped regions. The semantics of these I/O operations are emulated in a shim layer with memory-mapped regions by using a mapping between a process' address space and a file or shared memory object. Data that is protected from viewing by a guest OS running in a virtual machine may nonetheless be accessed by the process.

Abstract: A virtual-machine-based system that may protect the privacy and integrity of application data, even in the event of a total operating system compromise. An application is presented with a normal view of its resources, but the operating system is presented with an encrypted view. This allows the operating system to carry out the complex task of managing an application's resources, without allowing it to read or modify them. Different views of “physical” memory are presented, depending on a context performing the access. An additional dimension of protection beyond the hierarchical protection domains implemented by traditional operating systems and processors is provided.

Abstract: A virtual-machine-based system that identifies an application or process in a virtual machine in order to locate resources associated with the identified application. Access to the located resources is then controlled based on a context of the identified application. Those applications without the necessary context will have a different view of the resource.

Abstract: A virtual-machine-based system provides a control-transfer mechanism to invoke a user-mode application handler from existing virtual hardware directly, without going through an operating system kernel running in the virtual machine. A virtual machine monitor calls directly to the guest user-mode handler and the handler transfers control back to the virtual machine monitor, without involving the guest operating system.

Abstract: A virtual-machine-based system provides a mechanism for a virtual machine monitor (VMM) to process a hypercall received from an application running in the virtual machine (VM). A hypercall interface causes the virtual memory pages, needed by the VMM to process the hypercall, to be available to the VMM. In one embodiment, when virtual memory pages needed by the VMM to process the hypercall are not available to the VMM, the application is caused to access the needed pages, in response to which the required virtual memory becomes available to the VMM.

Abstract: One embodiment of the present invention is a method of operating a virtualization system, the method including: (a) instantiating a guest in a virtual machine of the virtualization system; and (b) monitoring execution of code registered for monitored execution in an execution context of the guest, wherein the monitoring is performed by the virtualization system and is hidden from computations of the guest.

Abstract: One embodiment of the present invention includes a method for: (a) executing guest computations in a virtual machine of the virtualization system; and (b) forcing execution of registered code into an execution context of the guest, wherein the forcing is performed from the virtualization system based on an execution trigger monitored without reliance on functionality of the guest software.