The focus in this task is on updating the timing properties of Solution_INTEG, like WCET of functions. This is necessary, since usually the target system already accommodating Solution_EXIST is different from the system which Solution_INTEG was developed on. There might be different ways of updating the timing properties. For instance, for worst-case execution times the following approaches are possible:
· Transforming Solution_INTEG’s timing properties from the old to the new hardware/software design architecture.
One possible method here is extrapolation, i.e. given an old value of a timing property, the new value is computed by applying an extrapolation formula. The simplest case is linear extrapolation. For example, if the processor clock rate changes, then the new WCET may be estimated as WCETnew = WCETold * Clockold / Clocknew, where Clock is the number of processor cycles per second. For this simple formula it is assumed that the number of processor cycles for reading and writing memory remains the same. Note, that extrapolation is a kind of estimation, so it may be necessary to add a safety margin to the new WCET and to classify it accordingly. One advantage is that extrapolation can be supported by tools.
· Measuring execution times of Solution_INTEG’s components on the new target – this follows a bottom-up approach and requires the availability of the target processor and the possibility of easily porting Solution_INTEG on the target processor before integration.
· Complete re-computation of the WCET by static analysis of the new function in the environment of Solution_BOTH. This also requires detailed knowledge about the implementation on the new target.
The methodology willnot give advice on how to update the necessary timing properties; this is subject to the specific characteristics of a particular project.
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