title: can LD_PRELOAD trick considered as a type of instrumentation?
body: <p>If you set <code>LD_PRELOAD</code> to the path of a shared object, that file will be loaded <strong>before</strong> any other library (including the C runtime, <code>libc.so</code>). This trick is used by a number of profilers, especially MPI profilers. My question is, can this pre-loading be considered as a type of instrumentation? If yes, will it be source level instrumentation or static binary instrumentation?</p>