Hi,
You would think that you are correct since the system should be
deterministic.
I don't have to think it, program output gives evidence. On P4 I get
just 80, on an Atom system I get 22-33-22-33-22-33-..., on a Bulldozer
40-44-40-44-40-... Once again, "[rdtsc readings] can form complex yet
periodic structure." Well, above are not exactly complex, but
undoubtedly periodic.
But it does not show such deterministic behavior. And
when you say that after a few hundred cycles all should be settled, why
do I see some 200,000 outputs from the code of yours on an otherwise
idle system?
It is *your* job to explain it.
So, what is so wrong to try to harvest the entropy on systems where it
is available? You try to smack down the entire approach because some or
even a large number of systems do not show that behavior. But still a
large number of systems DO show this behavior. And on those systems, we
should harvest it because all OSes are starved of entropy.
All I'm saying is that I can't find the analysis satisfactory. This
means that I also imply that suggested entropy value can be [grossly]
overestimated. I also argue that the phenomena is related to
interactions with memory subsystem.
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