1168 results about "Deadlock" patented technology

A graphical user interface (GUI) scheduler program is provided for modeling business workflow processes. The GUI scheduler program includes tools to allow a user to create a schedule for business workflow processes based on a set of rules defined by the GUI scheduler program. The rules facilitate deadlock not occurring within the schedule. The program provides tools for creating and defining message flows between entities. Additionally, the program provides tools that allow a user to define a binding between the schedule and components, such as COM components, script components, message queues and other workflow schedules. The scheduler program allows a user to define actions and group actions into transactions using simple GUI scheduling tools. The schedule can then be converted to executable code in a variety of forms such as XML, C, C+ and C++. The executable code can then be converted or interpreted for running the schedule.

The present invention provides a system and method for implementation and use of a shared memory. The shared memory may be accessed both independently and asynchronously by one or more processes at corresponding nodes, allowing data to be streamed to multiple processes and nodes without regard to synchronization of the plurality of processes. The various nodes may be adaptive computing nodes, kernel or controller nodes, or one or more host processor nodes. The present invention maintains memory integrity, not allowing memory overruns, underruns, or deadlocks. The present invention also provides for “push back” after a memory read, for applications in which it is desirable to “unread” some elements previously read from the memory.

An apparatus and method for scheduling execution of multiple threads on a shared processor resource is described in connection with a multithreaded multiprocessor chip. Using a thread selection policy that switches between available threads every cycle to give priority to the least recently executed or scheduled threads, different threads are able to operate in a way that ensures no deadlocks or livelocks while maximizing aggregate performance and fairness between threads. Prioritization is accomplished by monitoring and sorting thread status information for each thread, including speculative states in which a thread may be speculatively scheduled, thereby improving usage of the execution pipeline by switching a thread in with a lower priority.

A method of polling in a wireless communications system includes prohibiting polling within a first predetermined period and triggering a poll function while polling is prohibited. After the first predetermined period has expired the method determines that there are no protocol data units (PDUs) scheduled for transmission or re-transmission and that there is at least a transmitted PDU that is not acknowledged yet, and selects a PDU to schedule for re-transmission to fulfill the poll function.

A method of deadlock detection is disclosed which adjusts the detection technique based on statistics maintained for tracking the number of actual deadlocks that are detected in a distributed system, and for which types of locks are most frequently involved in deadlocks. When deadlocks occur rarely, the deadlock detection may be tuned down, for example, by reducing a threshold value which determines timeouts for waiting lock requests. When it is determined that actual deadlocks are detected frequently, the processing time for deadlock detection may be reduced, for example, by using parallel forward or backward search operations and/or by according higher priority in deadlock detection processing to locks which are more likely to involve deadlocks.

The invention relates to a dispatching and route-planning method for multiple AGVs used for material transportation in a factory. The method comprises the following steps: (1) modeling material transportation scenes in a factory, including the travelling routes of AGVs, AGV charging points, loading and unloading points and standby zones for AGVs; (2) storing allocated tasks in a queue; (3) findingout one AGV closest to a current-task issuing site from a set of available AGVs; (4) calculating the shortest route from a current-task start point and a current-task stop point by using an A* algorithm; and (5) calling a time-window algorithm for maintenance of a time-window vector table of the shortest route obtained in the step (4). Compared with traditional A* algorithms, a heuristic functionin the A* algorithm used in the invention takes the traveling cost and turning cost of the AGVs on roads in a workshop into consideration, the time-window vector table of each route section is maintained, and whether conflicts exist in planned routes is determined by judging whether superposition exists; so the problems of collision conflicts, deadlock and the like of AGV route planning are effectively overcome.

A graphics processing subsystem uses system memory as its graphics memory for rendering and scanout of images. To prevent deadlock of the data bus, the graphics processing subsystem may use an alternate virtual channel of the data bus to access additional data from system memory needed to complete a write operation of a first data. In communicating with the system memory, a data packet including extended byte enable information allows the graphics processing subsystem to write large quantities of data with arbitrary byte masking to system memory. To leverage the high degree of two-dimensional locality of rendered image data, the graphics processing subsystem arranges image data in a tiled format in system memory. A tile translation unit converts image data virtual addresses to corresponding system memory addresses. The graphics processing subsystem reads image data from system memory and converts it into a display signal.

Systems and methods described herein are directed to solutions for Network on Chip (NoC) interconnects that supports reconfigurability to support a variety of different traffic profiles each having different sets of traffic flows after the NoC is designed and deployed in a SoC. Reconfiguration of the NoC to map and load a new traffic profile or change the currently mapped traffic profile is performed by an external optimization module which maps various transactions of a given traffic profile to the NoC and reconfigure the NoC hardware by loading the computed mapping information. As part of the mapping process, load balancing between NoC layers may be performed by automatically assigning the transactions in the traffic profile to be routed over certain NoC layers and channels, automatically determining the routes based on the bandwidth requirements of the transaction. The deadlock avoidance and isolation properties of various transactions are maintained during the mapping.

A computer-implemented method for implementing a deadlock avoidance mechanism to prevent a plurality of threads from deadlocking in a computer system wherein a first thread of the plurality of threads request for a first resource is provided. The computer-implemented method includes employing the deadlock avoidance mechanism to intercept the request. The computer-implemented method also includes examining a status of the first resource. The computer-implemented method further includes, if the first resource is owned, identifying an owner of the first resource, analyzing the owner of the first resource to determine if the owner of the first resource is requesting a second resource, and analyzing the second resource to determine if the second resource is owned by the first thread. The computer-implemented method yet also includes, if the first thread owns the second resource, preventing deadlocking by handling a potential deadlock situation.

In certain, currently available data-storage systems, incoming commands from remote host computers are subject to several levels of command-queue-depth-fairness-related throttles to ensure that all host computers accessing the data-storage systems receive a reasonable fraction of data-storage-system command-processing bandwidth to avoid starvation of one or more host computers. Recently, certain host-computer-to-data-storage-system communication protocols have been enhanced to provide for association of priorities with commands. However, these new command-associated priorities may lead to starvation of priority levels and to a risk of deadlock due to priority-level starvation and priority inversion. In various embodiments of the present invention, at least one additional level of command-queue-depth-fairness-related throttling is introduced in order to avoid starvation of one or more priority levels, thereby eliminating or minimizing the risk of priority-level starvation and priority-related deadlock.

An improved computer memory subsystem determines the most efficient memory command to execute. The physical location and any address dependency of each incoming memory command to a memory controller is ascertained and that information accompanies the command for categorization into types of command. For each type of memory command, there exists a command FIFO and associated logic in which a programmable number of the memory commands are selected for comparison with each other, with the memory command currently executing, and with the memory command previously chosen for execution. The memory command having the least memory cycle performance penalty is selected for execution unless that memory command has an address dependency. If more than one memory command of that type has the least memory cycle performance penalty, then the oldest is selected for execution. Memory commands of that type are selected for execution each subsequent cycle until a valid memory command of that type is no longer available, or until a predetermined number has been executed, or until a memory command of another type has higher priority. If an address dependency exists between memory commands of different types, then memory commands of the same type of the oldest memory command is executed to avoid deadlock.

Systems and methods described herein are directed to solutions for Network on Chip (NoC) interconnects that support a variety of different component protocols each having different sets of data and/or metadata even after the NoC is designed and finalized. Example implementations include, automatically changing format of packets received from an originating SoC component by an originating bridge based on a NoC interface protocol and then transmitting the packet across the NoC interconnect to a destination bridge. The format may again be changed based on the protocol of the destination SoC component. The proposed protocol can be configured to map various transactions presented to it, be they packets belonging to the physical, data link layer, network layer or transport layer. As part of the mapping process, virtual channels for latency or deadlock avoidance may be created and may be maintained for the entire life of the packet within the NoC.

The present invention provides techniques by which updates may be incorporated in database indexes without causing deadlocks of user transactions. In deferred-incorporate update, the updates are propagated to the index only at transaction commit time. A method of handling transactions including updates in a database management system comprises the steps of receiving an update to a database maintained by the database management system, the update operable to cause an index of the database to be modified, recording the update in a log, and receiving an indication that the transaction is to be committed and in response, incorporating the update from the log into an index of the database. The update may comprise an insert operation and/or a delete operation.

A sensor network routing is formulated as a joint optimization problem taking into account routing cost and information aggregation. Information gain is used explicitly to optimize the routing path. The optimization approach involves a shortest path algorithm in a modified network graph. A method is provided that routes queries from an arbitrary entry point to high activity network sensor regions using inputs from sensor nodes along the path to refine the message. The multiple step look-ahead approach provides deadlock avoidance and routing around sensor network holes. For point-to-point query routing, a method based on real-time A* (RTA*) search is provided to find a path which takes detours efficiently to maximize information aggregation. Future information expected to be gained along the path from an arbitrary node to an exit node may be estimated to allow the selection of a successor sensor node.

Methods, apparatus and systems for memory access obscuration are provided. A first embodiment provides memory access obscuration in conjunction with deadlock avoidance. Such embodiment utilizes processor features including an instruction to enable monitoring of specified cache lines and an instruction that sets a status bit responsive to any foreign access (e.g., write or eviction due to a read) to the specified lines. A second embodiment provides memory access obscuration in conjunction with deadlock detection. Such embodiment utilizes the monitoring feature, as well as handler registration. A user-level handler may be asynchronously invoked responsive to a foreign write to any of the specified lines. Invocation of the handler more frequently than expected indicates that a deadlock may have been encountered. In such case, a deadlock policy may be enforced. Other embodiments are also described and claimed.

A multi-level locking hierarchy for a relational database includes a locking level applied to a multi-dimensionally clustering table, a locking level applied to blocks within the table, and a locking level applied to rows within the blocks. The hierarchy leverages the multi-dimensional clustering of the table data for efficiency and to reduce lock overhead. Data is normally locked in order of coarser to finer granularity to limit deadlock. When data of finer granularity is locked, data of coarser granularity containing the finer granularity data is also locked. Block lock durations may be employed to ensure that a block remains locked if any contained row remains locked. Block level lock attributes may facilitate detection of at least one of a concurrent scan and a row deletion within a block. Detection of the emptying of a block during a scan of the block may bar scan completion in that block.

A method of simulating software by use of a computer includes executing a program inclusive of a plurality of threads by a hardware model implemented as software on a software simulator, utilizing a monitor function of the simulator to collect information about accesses by monitoring accesses made by the plurality of threads with respect to resources provided in the hardware model, utilizing the monitor function to detect, from the collected information, overlapping accesses made to an identical resource area by two or more of the threads, and utilizing the monitor function to generate a message for warning of the overlapping accesses.

The invention discloses a shared resource scheduling method and system used in distributed parallel processing. The method and system are based on a distributed operation mechanism. The shared resource scheduling units distributed in each processor subsystem are distributed in each shared Resource locks and resource request arbitration units are implemented. These distributed processing units communicate by sending messages (resource access requests/permissions) to each other through the switching unit. The shared resource scheduling unit in the processor subsystem uses virtual queue technology to manage all resource access requests in the data cache, that is, a special queue is specially opened for each accessible shared resource. Resource locks in shared resources are used to ensure the uniqueness of access to shared resources at any time. Resource locks have two states: lock occupation and lock release. The request arbitration unit in the shared resource uses a priority-based fair polling algorithm to arbitrate resource access requests from different processing nodes. The invention can effectively avoid the competition problem when each processing node accesses the shared resource, can also avoid the deadlock of the shared resource and the starvation problem of the processing node, and provides high-efficiency mutually exclusive access to the shared resource.

Aspects of the invention pertain to deterministic packet routing systems and methods in multiprocessor computing architectures. Packets are analyzed to determine whether they are memory request packets or memory reply packets. Depending upon the packet, it is routed through nodes in the multiprocessor computer architecture in either an XY or YX path. Request and reply packets are sent in opposing routes according to a deterministic routing scheme. Multiport routers are placed at nodes in the architecture to pass the packets, using independent request and response virtual channels to avoid deadlock conditions.