[SMPI] Change sampling behavior.
Before, in sampling mode, each sampled loop was executed once, and the process would inject the time it took immediately.
This lead to a simcall being executed, which would then yield execution and possibly give the hand to another process.
This was destroying the caches, and resulted in over-estimated times.
This modification holds the injected time until the end of the sampling phase, trying to do the most of it on one process, without swapping contextes in between.
TODO :
- check what happens if num sampling iters < num iters/process (mandatory swapping)
Issues might be triggered if process leaves sampling before reaching the given bounds first.
