actually, the pure marker overhead seems to be a regression:
why isnt the marker near zero-cost as it should be? (as long as they are
enabled but are not in actual use) 2% increase is _ALOT_. That's the
whole point of good probes: they do not slow down the normal kernel.
_Worst case_ it should be at most a few instructions overhead but that
does not explain the ~2% wall-clock time regression you measured here.
So there's something wrong going on - either markers have unacceptably
high cost, or the measurement is not valid.
Ingo
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