Instruction counts instead of wall clock time?

It would be interesting to investigate use of instruction counts (through Linux's perf module and similar tools on other platforms to access hardware performance counters) within pyperf.

See, for example, Nicholas Nethercote's experience with monitoring rustc performance:

Contrary to what you might expect, instruction counts have proven much better than wall times when it comes to detecting performance changes on CI, because instruction counts are much less variable than wall times (e.g. ±0.1% vs ±3%; the former is highly useful, the latter is barely useful). Using instruction counts to compare the performance of two entirely different programs (e.g. GCC vs clang) would be foolish, but it’s reasonable to use them to compare the performance of two almost-identical programs (e.g. rustc before PR #12345 and rustc after PR #12345). It’s rare for instruction count changes to not match wall time changes in that situation. If the parallel version of the rustc front-end ever becomes the default, it will be interesting to see if instruction counts continue to be effective in this manner.

Perhaps in an interpreter where dispatch overhead and boxing/unboxing cost can be significant this won't hold true due to small changes having the potential to cause to a much more significant change in cache misses, but it would still be worthwhile to investigate in my view.

The issue names no files or tests. Start by investigating how pyperf records wall-clock measurements and how Linux's perf module and hardware performance counters could be accessed, then compare whether instruction counts provide a useful alternative across supported platforms.