Abstract: Distributed I/O virtualization includes receiving, at a first physical node in a plurality of physical nodes, an indication of a request to transfer data from an I/O device on the first physical node to a set of guest physical addresses. An operating system is executing collectively across the plurality of physical nodes. It further includes writing data from the I/O device to one or more portions of physical memory local to the first physical node. It further includes mapping the set of guest physical addresses to the written one or more portions of physical memory local to the first physical node.

Abstract: In accordance with example implementations, a process includes associating a secondary computer system with a primary computer system. The secondary computer system includes a first virtual machine, which is hosted by a secondary set of physical computer nodes. The primary computer system has a primary role, and the primary role corresponds to a minimum physical resource allocation. The secondary computer system is associated with a secondary role, and the second computer system is provisioned with a second physical resource allocation, which is less than the minimum physical resource allocation. The process includes, responsive to the primary computer system failing and without rebooting the secondary computer system, preparing the secondary computer system to take over the primary role. The preparation includes adding at least one physical computer node to the secondary set of physical computer nodes to cause the second physical resource allocation to meet or exceed the minimum physical resource allocation.

Abstract: A technique includes receiving information relating to wear of computer nodes. Based on the information relating to the wear, the technique includes ranking the computer nodes according to respective expected remaining lifetimes of the computer nodes. The technique includes, responsive to an event that corresponds to at least one of a spare computer node being added to the system or a given computer node being removed from the system, reconfiguring the system based on the ranking.

Abstract: Handling frequently accessed pages is disclosed. An indication is received of a stalling event caused by a requested portion of memory being inaccessible. It is determined that the requested portion of memory is a frequently updated portion of memory. The stalling event is handled based at least in part on the determination that the requested portion of memory is a frequently updated portion of memory.

Abstract: Dynamic adaptive reconfiguration of a computing system includes receiving a request to remove a first node in a plurality of physical nodes. An operating system is executing collectively across the plurality of physical nodes, and an application is running on the operating system. It further includes in response to the request, and while the application is running, evacuating virtualized resources associated with the first node to one or more other nodes in the plurality of physical nodes. It further includes subsequent to the evacuation of the virtualized resources, removing the first node from the plurality of physical nodes.

Abstract: In some examples, based on the information relating to the wear of physical memories in computer nodes of the distributed system, a system initiates a migration of a memory page from a first physical memory in a first computer node to a second physical memory in a second computer node. As part of the migration, the system updates a mapping between a first address space accessible by programs in the distributed system and a physical address space comprising memory locations in the physical memories.

Abstract: Initializing a software-defined server having software-defined NUMA domains includes, when booting a virtual environment defined by a set of hyper-kernels running on a plurality of physically interconnected computing nodes, accessing information associated with a software-defined NUMA domain configuration. It further includes, based at least in part on the accessed information, assigning software-defined NUMA domains to computing nodes. It further includes assigning virtualized resources to the software-defined NUMA domains. Handling a stalling event involving software-defined NUMA domains includes receiving an indication that a core or hyperthread which instantiates a virtual processor cannot access a virtualized resource needed by the core or hyperthread.

Abstract: Utilizing a storage replica data structure includes receiving, at a hyper-kernel running on a computing node in a plurality of interconnected computing nodes, an indication of an operation pertaining to at least one of a guest physical memory address or a stable storage address. A guest operating system is run on a virtual environment that is defined by a set of hyper-kernels running on the plurality of interconnected computing nodes. It further includes updating a storage replica data structure. The storage replica data structure comprises a set of entries.

Abstract: Handling frequently accessed pages is disclosed. An indication is received of a stalling event caused by a requested portion of memory being inaccessible. It is determined that the requested portion of memory is a frequently updated portion of memory. The stalling event is handled based at least in part on the determination that the requested portion of memory is a frequently updated portion of memory.

Abstract: Entanglement of pages and threads is disclosed. An indication is received of a stalling event caused by a requested portion of memory being inaccessible. It is determined that the requested portion of memory is an entangled portion of memory that is entangled with a physical node in a plurality of physical nodes. A type of the entangled portion of memory is determined. The stalling event is handled based at least in part on the determined type of the entangled portion of memory.

Abstract: Handling frequently accessed pages is disclosed. An indication is received of a stalling event caused by a requested portion of memory being inaccessible. It is determined that the requested portion of memory is a frequently updated portion of memory. The stalling event is handled based at least in part on the determination that the requested portion of memory is a frequently updated portion of memory.

Abstract: Dynamic adaptive reconfiguration of a computing system includes receiving a request to remove a first node in a plurality of physical nodes. An operating system is executing collectively across the plurality of physical nodes, and an application is running on the operating system. It further includes in response to the request, and while the application is running, evacuating virtualized resources associated with the first node to one or more other nodes in the plurality of physical nodes. It further includes subsequent to the evacuation of the virtualized resources, removing the first node from the plurality of physical nodes.

Abstract: Utilizing a storage replica data structure includes receiving, at a hyper-kernel running on a computing node in a plurality of interconnected computing nodes, an indication of an operation pertaining to at least one of a guest physical memory address or a stable storage address. A guest operating system is run on a virtual environment that is defined by a set of hyper-kernels running on the plurality of interconnected computing nodes. It further includes updating a storage replica data structure. The storage replica data structure comprises a set of entries.

Abstract: Initializing a computing system using dormant pages includes marking a set of guest physical addresses as dormant. It further includes, for each node in a plurality of physical nodes, designating a set of real physical addresses for zeroing. An operating system is executing collectively across the physical nodes.

Abstract: Dynamic adaptive reconfiguration of a computing system includes receiving a request to remove a first node in a plurality of physical nodes. An operating system is executing collectively across the plurality of physical nodes, and an application is running on the operating system. It further includes in response to the request, and while the application is running, evacuating virtualized resources associated with the first node to one or more other nodes in the plurality of physical nodes. It further includes subsequent to the evacuation of the virtualized resources, removing the first node from the plurality of physical nodes.

Abstract: Dynamic scheduling is disclosed. A plurality of physical nodes is included in a computer system. Each node includes a plurality of processors. Each processor includes a plurality of hyperthreads. In response to receiving an indication of an event occurring, a search is performed for a queue in a set of queues on which to place a virtual processor that had been waiting on the event. Queues in the set of queues correspond to hyperthreads in a physical node in the plurality of physical nodes. The queues in the set of queues are visited according to a predetermined traversal order.

Abstract: Utilizing a storage replica data structure includes receiving, at a hyper-kernel running on a computing node in a plurality of interconnected computing nodes, an indication of an operation pertaining to at least one of a guest physical memory address or a stable storage address. A guest operating system is run on a virtual environment that is defined by a set of hyper-kernels running on the plurality of interconnected computing nodes. It further includes updating a storage replica data structure. The storage replica data structure comprises a set of entries. The set of entries in the storage replica data structure comprises associations among guest physical memory addresses, physical memory addresses, and stable storage addresses.

Abstract: Hierarchical stalling strategies are disclosed. An indication is received of a stalling event caused by a requested resource being inaccessible. In response to receiving the indication of the stalling event, a set of cost functions usable to determine how to handle the stalling event is selected based at least in part on a type of the stalling event. The stalling event is handled based at least in part on an evaluation of the set of cost functions selected based at least in part on the type of the stalling event.

Abstract: Utilizing a storage replica data structure includes receiving, at a hyper-kernel running on a computing node in a plurality of interconnected computing nodes, an indication of an operation pertaining to at least one of a guest physical memory address or a stable storage address. A guest operating system is run on a virtual environment that is defined by a set of hyper-kernels running on the plurality of interconnected computing nodes. It further includes updating a storage replica data structure. The storage replica data structure comprises a set of entries.

Abstract: Resource migration negotiation is disclosed. A request is received, from a remote physical node in a plurality of physical nodes, for a resource. An operating system is run collectively across the plurality of physical nodes. The request includes information pertaining to a guest thread running on the remote physical node. Based at least in part on at least some of the information included in the request, it is determined whether to send the requested resource or reject the request. A response is provided based at least in part on the determination.