Abstract: According to one aspect of the invention, a request to generate a state checkpoint of a computer is initiated within a user-level software entity, such as a virtual machine. Upon sensing the request, a checkpointing mechanism generates and stores at least one checkpoint, each checkpoint comprising a representation of the total state of the computer system. Upon sensing a state restoration request corresponding to one of the checkpoints, the checkpointing mechanism restores the checkpointed state in the computer, which can then resume operation from the restored total state. According to another aspect of the invention, a total checkpointed state is exported to another computer, where the state can be modified, for example, debugged, and then loaded into either the originally checkpointed computer (which, again, may be a virtual machine), or some other computer.

Abstract: According to one aspect of the invention, a request to generate a state checkpoint of a computer is initiated within a user-level software entity, such as a virtual machine. Upon sensing the request, a checkpointing mechanism generates and stores at least one checkpoint, each checkpoint comprising a representation of the total state of the computer system. Upon sensing a state restoration request corresponding to one of the checkpoints, the checkpointing mechanism restores the checkpointed state in the computer, which can then resume operation from the restored total state. According to another aspect of the invention, a total checkpointed state is exported to another computer, where the state can be modified, for example, debugged, and then loaded into either the originally checkpointed computer (which, again, may be a virtual machine), or some other computer.

Abstract: According to one aspect of the invention, a request to generate a state checkpoint of a computer is initiated within a user-level software entity, such as a virtual machine. Upon sensing the request, a checkpointing mechanism generates and stores at least one checkpoint, each checkpoint comprising a representation of the total state of the computer system. Upon sensing a state restoration request corresponding to one of the checkpoints, the checkpointing mechanism restores the checkpointed state in the computer, which can then resume operation from the restored total state. According to another aspect of the invention, a total checkpointed state is exported to another computer, where the state can be modified, for example, debugged, and then loaded into either the originally checkpointed computer (which, again, may be a virtual machine), or some other computer.

Abstract: According to one aspect of the invention, a request to generate a state checkpoint of a computer is initiated within a user-level software entity, such as a virtual machine. Upon sensing the request, a checkpointing mechanism generates and stores at least one checkpoint, each checkpoint comprising a representation of the total state of the computer system. Upon sensing a state restoration request corresponding to one of the checkpoints, the checkpointing mechanism restores the checkpointed state in the computer, which can then resume operation from the restored total state. According to another aspect of the invention, a total checkpointed state is exported to another computer, where the state can be modified, for example, debugged, and then loaded into either the originally checkpointed computer (which, again, may be a virtual machine), or some other computer.

Abstract: In a virtualized system running one or more virtual machines on a first hypervisor, a second hypervisor is installed and control of the hardware resources of the physical computer supporting the virtualized system is migrated from the first hypervisor to the second hypervisor without interrupting the operation of the first hypervisor and the virtual machines. Initially a minimal set of hardware resources is hot-removed from control by the first hypervisor, and the second hypervisor is launched on the minimal set of hardware resources. Both the remaining hardware resources and the virtual machines are then migrated from the first hypervisor to the second hypervisor until all the virtual machines have been migrated over to the second hypervisor, while the virtual machines and the first hypervisor continue running largely unaffected by the migration process.

Abstract: In a virtualized system running one or more virtual machines on a first hypervisor, a second hypervisor is installed and control of the hardware resources of the physical computer supporting the virtualized system is migrated from the first hypervisor to the second hypervisor without interrupting the operation of the first hypervisor and the virtual machines. Initially a minimal set of hardware resources is hot-removed from control by the first hypervisor, and the second hypervisor is launched on the minimal set of hardware resources. Both the remaining hardware resources and the virtual machines are then migrated from the first hypervisor to the second hypervisor until all the virtual machines have been migrated over to the second hypervisor, while the virtual machines and the first hypervisor continue running largely unaffected by the migration process.

Abstract: In a virtualized system running one or more virtual machines on a first hypervisor, a second hypervisor is installed and control of the hardware resources of the physical computer supporting the virtualized system is migrated from the first hypervisor to the second hypervisor without interrupting the operation of the first hypervisor and the virtual machines. Initially a minimal set of hardware resources is hot-removed from control by the first hypervisor, and the second hypervisor is launched on the minimal set of hardware resources. Both the remaining hardware resources and the virtual machines are then migrated from the first hypervisor to the second hypervisor until all the virtual machines have been migrated over to the second hypervisor, while the virtual machines and the first hypervisor continue running largely unaffected by the migration process.

Abstract: In a virtualized system running one or more virtual machines on a first hypervisor, a second hypervisor is installed and control of the hardware resources of the physical computer supporting the virtualized system is migrated from the first hypervisor to the second hypervisor without interrupting the operation of the first hypervisor and the virtual machines. Initially a minimal set of hardware resources is hot-removed from control by the first hypervisor, and the second hypervisor is launched on the minimal set of hardware resources. Both the remaining hardware resources and the virtual machines are then migrated from the first hypervisor to the second hypervisor until all the virtual machines have been migrated over to the second hypervisor, while the virtual machines and the first hypervisor continue running largely unaffected by the migration process.

Abstract: According to one aspect of the invention, a request to generate a state checkpoint of a computer is initiated within a user-level software entity, such as a virtual machine. Upon sensing the request, a checkpointing mechanism generates and stores at least one checkpoint, each checkpoint comprising a representation of the total state of the computer system. Upon sensing a state restoration request corresponding to one of the checkpoints, the checkpointing mechanism restores the checkpointed state in the computer, which can then resume operation from the restored total state. According to another aspect of the invention, a total checkpointed state is exported to another computer, where the state can be modified, for example, debugged, and then loaded into either the originally checkpointed computer (which, again, may be a virtual machine), or some other computer.

Abstract: A computer architecture includes a first operating system (COS), which may be a commodity operating system, and a kernel, which acts as a second operating system. The COS is used to boot the system as a whole. After booting, the kernel is loaded and displaces the COS from the system level, meaning that the kernel itself directly accesses predetermined physical resources of the computer. All requests for use of system resources then pass via the kernel. System resources are divided into those that, in order to maximize speed, are controlled exclusively by the kernel, those that the kernel allows the COS to handle exclusively, and those for which control is shared by the kernel and COS. In the preferred embodiment of the invention, at least one virtual machine (VM) runs via a virtual machine monitor, which is installed to run on the kernel. Each VM, the COS, and even each processor in a multiprocessor embodiment, are treated as separately schedulable entities that are scheduled by the kernel.

Abstract: A computer architecture includes a first operating system (COS), which may be a commodity operating system, and a kernel, which acts as a second operating system. The COS is used to boot the system as a whole. After booting, the kernel is loaded and displaces the COS from the system level, meaning that the kernel itself directly accesses predetermined physical resources of the computer. All requests for use of system resources then pass via the kernel. System resources are divided into those that, in order to maximize speed, are controlled exclusively by the kernel, those that the kernel allows the COS to handle exclusively, and those for which control is shared by the kernel and COS. In the preferred embodiment of the invention, at least one virtual machine (VM) runs via a virtual machine monitor, which is installed to run on the kernel. Each VM, the COS, and even each processor in a multiprocessor embodiment, are treated as separately schedulable entities that are scheduled by the kernel.

Abstract: A computer system is interrupted, and its entire state information is extracted as one or more checkpoints at one or more respective points during operation of the system. The checkpoint may be restored into the system at any later time, even multiple times, and it may also even be loaded into one or more other systems; all systems loaded with the same checkpoint will then execute from the same checkpointed state. The state extraction mechanism is preferably a virtual machine monitor, on which one or more virtual machines are installed, each virtual machine constituting an encapsulated, virtualized computer system whose states can be checkpointed under control of the virtual machine monitor. Checkpoints may be stored on a portable memory device or transmitted as a batch or dynamically over a network so that even virtual machines installed at different sites may execute from the same state.

Abstract: One or more virtual machines (VM's) run via a virtual machine monitor (VMM) on a hardware platform that has a segmented memory architecture. Each VM has at least one VM descriptor table that has, as entries, VM segment descriptors. At least one VMM descriptor table is established, including at least one shadow descriptor table that stores shadow descriptors for certain of the VM segment descriptors, which are then shadowed descriptors. The VMM compares the shadow descriptors with their respective corresponding shadowed VM descriptors, detects any lack of correspondence between the shadow descriptor table and the corresponding VM descriptor table, and updates and thereby synchronizes each shadow descriptor with its respective shadowed VM descriptor no later than, and preferably only upon the first use of, the respective descriptor by the VM.

Abstract: A method of providing coherent shared memory access among a plurality of shared memory multiprocessor nodes. For each line of data in each of the nodes, a list of those processors of the node that have copies of the line in their caches is maintained. If a memory command is issued from a processor of one node, and if the command is directed to a line of memory of another node, then the memory command is sent directly to an adapter of the one node. When the adapter receives the command, it forwards the command from the one adapter to another adapter of the other node. When the other adapter receives the command, the command is forwarded to the local memory of the other node. The list of processors is then updated in the local memory of the other node to include or exclude the other adapter depending on the command. If the memory command is issued from one of the processors of one of the nodes, and if the command is directed to a line of memory of the one node, then the command is sent directly to local memory.

Abstract: A mechanism to dynamically migrate a home node of a global page to a more suitable node for improving performance of parallel applications running on a S-COMA and other DSM systems. More specifically, consultation counts are maintained at each client node of a shared memory system, where the consultation count indicates the number of times the client node has consulted the dynamic for lines a page. This information is then used along with other information to decide on whether to change the dynamic home node to a more suitable node.

Abstract: A method and apparatus for maintaining cache coherence in a shared memory multiprocessor system, where cache coherence is preserved between lock acquires and releases rather than at every single memory load and store. With this invention, a Global Lock Manager (GLM) keeps track of the status of locked ranges without the need to maintain a list of individual processors in the system. Further a Recently Acquired Lock Manager (RALM) keeps track of the status of locked ranges within a processing node to reduce the need to communicate with a GLM.