Mill Computing, Inc. Forums The Mill Architecture Grab bag of questions Reply To: Grab bag of questions

Ivan Godard
Post count: 689

– 8) Profiling support
This too is mostly the domain of language and OS. The usual instrumentation methods will work on a Mill of course, but transparent instrumentation has really nasty issues with security that can only be addressed by the OS security model, not the architecture. Do you really want to give this turf the ability to dynamically change (i.e. instrument) the code being run by that turf?

In addition, like all wide machines the Mill presents an execution model that is not the single-program-sequence of a z80. What does it mean to single-step a program when it fires a dozen instructions at once, and retires them at a dozen different points in time? Our tools give us a good view of machine level debugging – but debugging and profiling Mill at the source level is just as hard as doing it for heavily optimized code on any architecture.

The tool chain does have a mode (still buggy) in which the code emulates a one-complete-instruction-at-a-time architecture, z80-ish. That helps with debugging and some profile questions like how many times was something called, but is completely useless for timing questions. These are human-factors questions for which nobody seems to have answers on any architecture.