LabVIEW Idea Exchange
The menu "tools...profile...find parallelizable loops" is a great tool to indentify loops that can be parallelized and it gives detailed advice and warnings in questionable cases.
There is however an important scenarios that is ignored in the analysis:
The case is if the parallelizable loop is contained inside a larger loop that is already parallelized. As a general rule, it is typically most efficient to parallelize the outermost loop only. A parallel loop inside a parallel loop only creates more overhead and will not gain much if the outer loop already causes 100% use of all CPU cores. It is possible that the LabVIEW compiler sorts things out automatically, but I think the "find parallelizable loops" tool should consider if an outer, already parallelized loop exists and should tone down the recommendation to a question mark instead of a check mark in this case.
Here is a typical analysis (yes, the subVI is very simple and inlined, so the outer loop parallelization is sound ;))
The description could read "This loop can be safely parallelized, but it is already contained inside a parallel loop and thus parallelization would not give any significant advantage" or similar.
Idea summary: The result window of "find parallelizable loops" should warn if a parallelizable loop is contained inside a parallel loop.
