From my understanding of real-time systems WCET typically depends
not only on the architecture of the target platform, but also on
the criticality of the system.
On Thursday, 14 April 2016 at 08:14:59 UTC, Johannes Pfau wrote:
Such deterministic code is usually very restricted. This is
expected. See also:
https://en.wikipedia.org/wiki/Worst-case_execution_time
Perhaps the best example of a restricted subset of a language
would be Ada's ravenscar profile, for High integrity real-time
systems:
http://www.dit.upm.es//~str/proyectos/ork/documents/RP_spec.pdf
As a compiler we can't give a useful estimate of WCET without
knowing the target architecture very well (calculating some
upper bound is not too difficult, but if you ignore pipelining
and caches the calculated WCET might be 4-5x higher than the
real WCET).
I am agreed on this, I fail to see how a complier could provide
any useful estimate. Not only does this measurement depend on the
target hardware, but on the criticality of the task - a
calculated upper bound is used for tasks with hard-deadlines, but
measurement is usually sufficient for tasks with soft deadlines.
