30 results about "Worst-case execution time" patented technology

An information processing system that can reduce its power consumption by means of robust power controlling even upon occurrence of an interruption / exception processing. If it is found that there is no task set in the ready state as a result of watching the number of tasks set in the ready state by the RTOS or ready state watching task, the system controls the RTOS or ready state watching task so as to lower the power while the current active task controls the power according to the preset WCET of each application slice. On the contrary, if there is any task set in the ready state, the system controls so as to raise the power and the current active task comes to control the power according to the virtual WCET that is earlier than the WCET of each application slice. And, if there is no task set in the ready state and there is no current active task, the system controls so that the RTOS or both of the ready state watching task and sleep task lower the power. This is why the present invention can reduce the power consumption of the subject information processing system.

Signal stream processing jobs contain tasks (100), each task (100) to be performed by repeated execution of an operation that processes a chunk of data from a stream. Each job comprises a plurality of the tasks (100) in stream communication with one another. A plurality of processing units (10), which are mutually coupled for the communication of signal streams execute that tasks. A preliminary computation is performed for each job individually, to determine execution parameters required for the job to support a required minimum stream throughput rate if each task of the job is executed in a respective context wherein opportunities to start execution of the task occur separated at most by a cycle time T defined for the task. At run time combination of jobs is selected for execution. Groups of the tasks of the selected combination of jobs are assigned to respective ones of the processing units (10), checking that for each particular processing unit (10) a sum of worst case execution times for the tasks assigned to that particular processing unit (10) does not exceed the defined cycle time T defined for any of the tasks (100) assigned to the particular processing unit (10). The processing unit (10) execute the selected combination of jobs concurrently, each processing unit (10) time multiplexing execution of the group of tasks (100) assigned to that processing unit (10).

Disclosed are a partial heap garbage collector, and a partial heap garbage collection method, that during collection checks the time remaining (or equivalently the time taken so far, or the work done so far) to complete the partial heap collection. In a preferred embodiment, the partial heap collection is guaranteed to complete within a fixed time interval. For example, this guarantee may be obtained by applying a worst-case execution time (WCET) and sizing a nursery so that complete evacuation of the nursery can always be achieved on time. As an alternative, a technique, referred to as syncopation, may be used to allow generational collection to be used despite variance in program behavior over the short time scales in which a nursery can be collected. Syncopation may be accomplished via allocation control or via collection control.

Systems and Methods for task allocation in a multiprocessor environment employing power management techniques are described wherein tasks are allocated relative to the density given by the ratio of worst-case-execution time and deadline of a task and also the harmonicity of a task's period with respect to a task-set. Tasks are allocated to a given processor based on either minimum density or maximum harmonicity depending on which allocation results in a lower clock frequency. Assigning a task to the processor with lowest density results in balancing the density across processors while assigning task to the processor with maximum harmonicity attempts to maximize the utilization of the processor.

A method of controlling a system comprising the following steps: - launching a task, said task being associated with a worst case execution time; and - monitoring the end of the task after a time slot allocated to the execution of the task; wherein said time slot is shorter than said worst case execution time.

The invention relates to an automatic method for exactly analyzing WCET (Worst-Case Execution Time) of a task, which comprises the following steps: 1) generating a no loop control flow graph NLCFG of a program; 2) utilizing the NLCFG to confirm a depending input variable and a corresponding node thereof; 3) confirming a depending cyclic variable, a depending non-input branch variable and non-depending input nodes corresponding to the depending cyclic variable and the depending non-input branch variable; 4) deleting the non-depending input nodes and generating an ICFG (input control flow graph); 5) generating all paths of the ICFG; 6) generating an input condition for each path and the WCET corresponding to each path. The condition of each path and the corresponding WCET can be utilized to accurately estimate the WCET of the task.

A shared memory computing device optimised for worst case execution time analysis that has at least one interconnect master, N cache modules and N processor cores. Each cache module has a finite state machine that employs an update-type cache coherency policy. Each processor core is assigned a different one of the N fully associative cache modules as its private cache. Furthermore, the execution time of memory transfer requests issued by each of the N processor cores is not modified by: (a) the unrelated memory transfer requests issued by any of the other N processor cores; or (b) the unrelated memory transfer requests issued by at least one other interconnect master.

Signal stream processing jobs contain tasks (100), each task (100) to be performed by repeated execution of an operation that processes a chunk of data from a stream. Each job comprises a plurality ofthe tasks (100) in stream communication with one another. A plurality of processing units (10), which are mutually coupled for the communication of signal streams execute that tasks. A preliminary computation is performed for each job individually, to determine execution parameters required for the job to support a required minimum stream throughput rate if each task of the job is executed in a respective context wherein opportunities to start execution of the task occur separated at most by a cycle time T defined for the task. At run time combination of jobs is selected for execution. Groupsof the tasks of the selected combination of jobs are assigned to respective ones of the processing units (10), checking that for each particular processing unit (10) a sum of worst case execution times for the tasks assigned to that particular processing unit (10) does not exceed the defined cycle time T defined for any of the tasks (100) assigned to the particular processing unit (10). The processing unit (10) execute the selected combination of jobs concurrently, each processing unit (10) time multiplexing execution of the group of tasks (100) assigned to that processing unit (10).

The invention relates to a task scheduling method based on a task application signal and an execution cost value of a processor core. The task scheduling method comprises the following steps: (1) the task application signal: a global linked list and a processor core scheduling queue are adopted to record a task; (2) the execution cost value of the processor core: each processor core maintains one execution cost value vector, and the processor core calculates to obtain the execution cost value of each task in the global linked list, and stores the execution cost value of each task into the execution cost value vector; and (3) task scheduling probability: the processor core calculates the probability for scheduling the task to the processor core scheduling queue from the global linked list according to the execution cost value of the task and the application signal of the task. The global linked list and the processor core scheduling queue are adopted to record tasks, the application signal intensity of the task and the task execution cost value of the processor core are used as task scheduling criterions, cost generated in a task transfer process can be effectively reduced, and task execution time is shortened.

The invention provides a distribution function-based WCET (Worst Case Execution Time) quick estimation method. The method comprises the following steps: disassembling a DSP (Digital Signal Processor) project objective code (out file) to obtain a disassembled file F; analyzing the disassembled file F to acquire each divided basic block to obtain a basic block set B of a program; recognizing relation between every two basic blocks in the basic block set B to construct a program flow graph C; calculating execution time T of each basic block; obtaining weighted program flow graph Cw by weighting the basic block execution time T and the basic block execution frequency Ts; analyzing the weighted program flow graph Cw to obtain a path with the maximum total weight value and taking the maximum total weight value as the WCET. The defect that a program is required to be operated to obtain a test sample in the prior art is overcome, and the problems of more manual intervention and irrationality of a beta distribution parameter estimation method in the conventional PERT (Program Evaluation and Review Technique) are solved.

The invention relates to an analysis method for accurately calculating WCET (worst case execution time) of a task high-speed cache. The method comprises the following steps of firstly, generating the iteration range of a basic block; then, according to the iteration range of the basic block, calculating the iteration range of an instruction block, and finding the minimum iteration range of all instruction blocks from the calculated iteration range of the instruction block; according to the minimum iteration range of the instruction blocks, calculating the loss times, and removing the minimum iteration range; finally, according to the minimum iteration range, calculating the total maximum loss times of the high-speed cache, so as to calculate the WCET of the task high-speed cache. The method has the advantage that the estimating accuracy of the WCET of the high-speed cache can be obviously improved.

The invention provides a probabilistic real-time task scheduling method based on pWCET shaping, which belongs to the technical field of real-time systems. The present invention proposes a probabilistic real-time task scheduling scheme based on probabilistic worst-case execution time shaping to achieve the goal of properly isolating the influence between probabilistic real-time tasks and reducing the computational complexity of system schedulability analysis. The present invention shapes the pWCET of the probabilistic real-time task and allocates the execution budget based on the shaped pWCET. While meeting the probabilistic real-time requirements of each task, it can properly isolate the influence between the probabilistic real-time tasks, so that the entire task set The schedulability is significantly improved. In addition, the value of pWCET after shaping is significantly lower than that of the original pWCET, which can reduce the computational complexity of schedulability analysis and significantly improve efficiency.

The invention provides an instruction prefectching content selecting method for optimizing WCET (worst-case execution time) of a real-time task. A hardware structure of a basic-block information table (BBIT) is added in high-speed caching hardware of an existing instruction. The instruction prefectching content selecting method includes: initializing hardware configuration, collecting a static routine base block set via a compiler or a static routine character analyzing tool, removing base blocks only covering one storage block, collecting execution frequentness of every program base block under worst-case execution condition, sequencing the program base blocks according to the execution frequentness, selecting information of an appointed amount of program base blocks according to the sequence, and storing the information in the BBIT. During a high-speed cache accessing process, high-speed instruction cache and the BBIT are searched at the same time, high-speed instruction cache accessing loss under the worst-case execution condition can be effectively avoided, requirements on the real-time task are met, and meanwhile, the instruction prefectching content selecting method can effectively reduce hardware design cost, and is simple and direct to realize.

A robust system control method with short execution time limit. A method of controlling a system is provided, comprising the steps of: initiating a task, the task being associated with a worst case execution time; and monitoring the end of the task after a time slot allocated to execution of the task; wherein the time slot Shorter than the worst case execution time stated.

A system and method for optimized operation of real-time control applications. The system and method being configured for identifying and processing recurring code sequences in control applications to quantify the execution time of control applications, wherein for each set up and / or control application a timing data structure is generated to determine the execution time of control applications in industrial automation, determining execution times of control applications based on recurring code sequences that are automatically extracted from a set of training applications and / or identified in the respective application, automatically generating test data to determine their on-target execution times for refinement of the timing data structure, decomposing the structure of the respective control application into code sequences for which the created data timing structure and timing model respectively provide execution time estimates, and determining at least an estimate for the best-case execution time and / or the worst-case execution time of the control application.