Getting exact process information is tough, especially when the tool one uses is not behaving as one expects. To ease the matter somewhat, I drew a graph that show exactly how perfctr calls the interrupt handler and sets the offending process’ signal.
The idea is to assemble correct information on the event counts per fixed intruction count interval of e.g., 100M instructions. However, due to the non-deterministic nature of a multitasking kernel, sometimes we see IPC values that are … unexpected. Hopefully this graph sets us on the right track once more. In normal circumstances, having a few counts off track, is not too bad, but for the work we’re currently doing, we require correct counts.