Automatic method for exactly analyzing WCET (Worst-Case Execution Time) of task

An analytical task and precise technology, applied in the direction of program control devices, etc., can solve problems such as degrading system performance, aircraft bombing, leakage, etc., to achieve the effect of improving estimation accuracy

CN104391684AInactive Publication Date: 2015-03-04LUOYANG INST OF SCI & TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2015-03-04
Estimated Expiration
Not applicable · inactive patent

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Abstract

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.
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Description

technical field

[0001] The invention relates to an automatic method for accurately estimating the Worst Case Execution Time (WCET: Worst-Case Execution Time) of a real-time system task, belonging to the field of real-time embedded systems. Background technique

[0002] Different from general-purpose computer systems, the results of real-time systems are valid only when they are completed within the specified time range. If they are not completed within the specified time range, the performance of the system will be reduced at the slightest, and catastrophic consequences will be caused at worst. Such as aircraft bombing, nuclear leakage. Therefore, for real-time systems, it is particularly important to obtain the WCET and best-case execution time (BCET: Best-Case Execution Time) of each task in the system in advance. Given that BECT analysis is the same technique as WCET analysis, one only refers to WCET analysis. In fact, WCET analysis is the premise of real-time system ta...

Examples

Embodiment 1

[0070] The present invention will be further described in detail below in conjunction with the accompanying drawings. These implementation examples are described in sufficient detail to enable those skilled in the art to practice the invention.

[0071] The present invention proposes an automatic method for accurately generating program WCET. The method uses a graph similar to a program control flow graph (CFG, Control Flow Graph) to automatically generate task WCET situation expressions, thereby achieving the purpose of accurately estimating task WCET.

[0072] The method that the automatic and accurate generation program WCET that the present invention proposes comprises 6 steps, and concrete steps are as follows:

[0073] Step 1: Generate the program's acyclic control flow graph NLCFG

[0074] Similar to the CFG that generates programs, it also uses the three basic statements of the program: compound statements, conditional statements, and loop statements to generate three...