921results about "Program saving/restoring" patented technology

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.

According to some embodiments, a multithreaded microcontroller includes a thread control unit comprising thread control hardware (logic) configured to perform a number of multithreading system calls essentially in real time, e.g. in one or a few clock cycles. System calls can include mutex lock, wait condition, and signal instructions. The thread controller includes a number of thread state, mutex, and condition variable registers used for executing the multithreading system calls. Threads can transition between several states including free, run, ready and wait. The wait state includes interrupt, condition, mutex, I-cache, and memory substates. A thread state transition controller controls thread states, while a thread instructions execution unit executes multithreading system calls and manages thread priorities to avoid priority inversion. A thread scheduler schedules threads according to their priorities. A hardware thread profiler including global, run and wait profiler registers is used to monitor thread performance to facilitate software development.

A unified architecture for dynamic generation, execution, synchronization and parallelization of complex instructions formats includes a virtual register file, register cache and register file hierarchy. A self-generating and synchronizing dynamic and static threading architecture provides efficient context switching.

An apparatus and method for performing multithreaded operations includes partitioning the general purpose and/or floating point processor registers into register subsets, including overlapping register subsets, allocating the register subsets to the threads, and managing the register subsets during thread switching. Register overwrite buffers preserve thread resources in overlapping registers during the thread switching process. Thread resources are loaded into the corresponding register subsets or, when overlapping register subsets are employed, into either the corresponding register subset or the corresponding register overwrite buffer. A thread status register is utilized by a thread controller to keep track of READY/NOT-READY threads, the active thread, and whether single-thread or multithread operations are permitted. Furthermore, the registers in the register subsets include a thread identifier field to identify the corresponding thread. Register masks may also be used to identify which registers belong to the various register subsets.

Prior to or while the state of a virtual machine (“VM”) is being saved, such as in connection with the suspension or checkpointing of a VM, a set of one or more “active” memory pages is identified, this set of active memory pages comprising memory pages that are in use within the VM before operation of the VM is suspended. This set of active memory pages may constitute a “working set” of memory pages. To restore the state of the VM and resume operation, in some embodiments, (a) access to persistent storage is restored to the VM, device state for the VM is restored, and one or more of the set of active memory pages are loaded into physical memory; (b) operation of the VM is resumed; and (c) additional memory pages from the saved state of the VM are loaded into memory after operation of the VM has resumed.

During a process of migrating a source system into a standardized virtual environment, virtual machine instances of the source system executing in a hypervisor are snapshotted as virtual machine images in an operational repository of the hypervisor. The virtual machine images in the operational repository are short-term snapshots. From time to time during the migration process, long-term snapshots of the source system are created by checking given ones of the virtual machine images from the hypervisor operational repository into an image library as image objects.

A single chip microcomputer comprises a central processing unit (CPU) 2, a on-chip RAM 3, a on-chip ROM 5, a first bus DBUS for connecting the CPU, RAM, and ROM with one another and transferring data between them, a second bus ABUS for passing address data corresponding to the data passed through the first bus, a third bus SDBUS for connecting the CPU 2 with the RAM 3 and transferring data between them, the number of bits of the third bus SDBUS being larger than that of the first bus DBUS, and a fourth bus BABUS for connecting the CPU 2 with the RAM 3 and passing address data corresponding to the data passed through the third bus SDBUS. The CPU 2 has a data memory RF serving as general purpose registers for providing internal data to the third bus SDBUS, and a bank specifying register BP for holding positional data of a mapping region in the RAM 3 where the contents of the data memory RF are mapped and providing the positional data to the fourth bus BABUS. The RAM 3 has a memory cell array 31, a bank address control circuit 35 connected to the fourth bus BABUS, for generating a real address according to the contents of the bank specifying register BP (BP0, BP1), and a selection circuit 37 for selecting the real address generated by the bank address control circuit 35, or the address provided through the second bus ABUS.

A method for migrating virtual machines between hypervisors is disclosed. Initially, metadata describing a virtual machine are automatically scanned and parsed. The structure of the metadata of a source virtual machine are automatically analyzed. Elements of this structure are mapped to corresponding entries of a target virtual machine. A target metadata descriptor to be used as part of the target virtual machine is generated. A predefined layout description of the data stored in a file system image of the source virtual machine read. A predefined layout description of the data to be stored in a file system image to be used at the target virtual machine is also read. The data are extracted from the source virtual machine. A template of a file system image for the target virtual system is generated. Storage space corresponding to the target virtual machine is allocated, and the extracted data are inserted into the allocated storage space.

A processing system comprises a first processor that has active and inactive states and that processes at least one thread during the active state. A second processor has active and inactive states. The second processor consumes less power when operating in the active state than the first processor operating in the active state. A control module communicates with the first and second processors and selectively transfers the at least one thread from the first processor to the second processor and selects the inactive state of the first processor. The second processor processes the at least one thread.

In the operation of a computer, a plurality of bytecode or pseudocode instructions, at least some of the pseudocode instructions comprising a plurality of machine code instructions, are stored in a computer memory. For each of a plurality of tasks or jobs to be performed by the computer, a respective virtual thread of execution context data is automatically created. The virtual threads each include (a) a memory location of a next one of the pseudocode instructions to be executed in carrying out the respective task or job and (b) the values of any local variables required for carrying out the respective task or job. At least some of the tasks or jobs each entails execution of a respective one of the pseudocode instructions comprising a plurality of machine language instructions. Each of the tasks or jobs are processed in a respective series of time slices or processing slots under the control of the respective virtual thread, and, in every context switch between different virtual threads, such context switch is undertaken only after completed execution of a currently executing one of the pseudocode instructions.

Embodiments of the present invention provide efficient scheduling in a multi-core processor environment. In some embodiments, each core is assigned, at most, one execution context. Each execution context may then asynchronously run on its assigned core. If execution context is blocked, then its dedicated core may be suspended or powered down until the execution context resumes operation. The processor core may remain dedicated to a particular thread, and thus, avoid the costly operations of a process or context switch, such as clearing register contents. In other embodiments, execution contexts are partitioned into two groups. The execution contexts may be partitioned based on various factors, such as their relative priority. One group of the execution contexts may be assigned their own dedicated core and allowed to run asynchronously. The other group of execution contexts, such as those with a lower priority, are co-scheduled among the remaining cores by the scheduler of the operating system.

A system and method for enabling multithreading in a embedded processor, invoking zero-time context switching in a multithreading environment, scheduling multiple threads to permit numerous hard-real time and non-real time priority levels, fetching data and instructions from multiple memory blocks in a multithreading environment, and enabling a particular thread to modify the multiple states of the multiple threads in the processor core.

Adaptive modifications of spinning and blocking behavior in spin-then-block mutual exclusion include limiting spinning time to no more than the duration of a context switch. Also, the frequency of spinning versus blocking is limited to a desired amount based on the success rate of recent spin attempts. As an alternative, spinning is bypassed if spinning is unlikely to be successful because the owner is not progressing toward releasing the shared resource, as might occur if the owner is blocked or spinning itself. In another aspect, the duration of spinning is generally limited, but longer spinning is permitted if no other threads are ready to utilize the processor. In another aspect, if the owner of a shared resource is ready to be executed, a thread attempting to acquire ownership performs a “directed yield” of the remainder of its processing quantum to the other thread, and execution of the acquiring thread is suspended.

In an application in which context switching often occurs such as in a real time OS, it is possible to significantly reduce the overhead caused by the context switching. The OS issues a Swap instruction and a context switch starts. The Swap instruction is issued together with a thread (i.e., context) ID to be replaced, to a thread control unit (9). The thread ID is used to uniquely identify threads stored in a context cache (8). The thread control unit (9) saves data from a register file (1) to the context cache (8) via a context-dedicated bus (12) and transmits data of a new thread from the context cache (8) to the register file (1). According to the thread ID received, the thread control unit (9) automatically interchanges the necessary number of data in the register file (1) and the data in the context cache (8).

Various embodiments of the present invention provide a mobile computing device that operates multiple, co-existing and independent operating system environments on a common kernel. A booting process for initiating a multiple operating system environment is also provided. Additionally, various embodiments of the present invention include processes for managing a switch between one operating system environment to a second operating system environment.

An event can be detected by an input device. The event may be determined to be a triggering event by comparing the event to a group of triggering events. A first prediction model corresponding to the event is then selected. Contextual information about the device specifying one or more properties of the computing device in a first context is then received, and a set of one or more applications is identified. The set of one or more applications may have at least a threshold probability of being accessed by the user when the event occurs in the first context. Thereafter, a user interface is provided to a user for interacting with the set of one or more applications.

Multi-threaded processing with reduced context switching is disclosed. Context switches may be avoided through the use of pre-emption notification, a pre-emption wait time attribute and a no-context-save yield.

Data is placed in tiered storage with a suitable granularity according to application characteristics. The storage apparatus comprises a controller for managing storage areas, provided by storage media of a plurality of types of varying performance, as pools, and for assigning the storage areas in page units to a virtual volume from any tiered storage among a plurality of types of tiered storage which the pool comprises in response to a data write request from the host computer, wherein, for specific data which is managed by the host computer, the controller specifies an area with a high referencing frequency among the specific data on the basis of organization information of the specific data, and moves this area to another of the tiered storage with a higher performance than an already assigned tiered storage.

A method and apparatus for reducing the amount of data copied during process switches. A method for reducing the amount of data copied during process switches is provided. In response to a processor performing a process switch to a process, a first write indication corresponding to the process is stored to indicate a first register file in the processor should not be saved. In response to the process causing the processor to write to the first register file, the first write indication is altered to indicate the first register file should be saved. In response to the processor performing a process switch from the process, a first value stored in the first register file is copied into a storage device accessible by the processor if the first write indication indicates the first register file should be saved.According to another aspect of the present invention, in response to a processor performing a process switch to a process, it is determined whether the process is likely to cause the processor to touch a first register file contained in the processor. If it was determined the process is likely to cause the processor to touch the first register file, a first value stored in a storage device accessible by the processor is loaded into the first register file. A first load indication is stored to indicate whether the first value was loaded in the preceding step. In response to the process attempting to cause the processor to touch the first register file while the first load indication indicates the first value is not loaded, the first value stored in the storage device is loaded into the first register file and the first load indication is altered to indicate the first value was loaded.