Re: support for asymmetric CPUs

Replying to several messages, including my own:

Although several people mentioned energy efficiency, that is not my
immediate goal.  At least with the Alder Lake CPUs, I suspect that the
difference in energy use between low load on P-cores and E-cores is
small.  These are not especially energy-efficient chips; the i7-12700K
is rated at a base power of 125 W, with a peak of 190 W.  Instead, I am
more interested in system throughput and sensible placement decisions
using fairly simple algorithms.  I plan to experiment with starting
most processes on E-cores, and promoting to P-cores as soon as they
start using much CPU time.  This should reserve the P-cores for the
processes that most need them, and keep the processes with lower
utilization from interrupting them and disturbing caches.  In any case,
I'm hoping that simple algorithms can beat random placement.  Naively,
I hope that similar strategies would also lower power consumption for
varying workloads with mixed core types, although not as much as
algorithms that were more sensitive to efficiency of different types
of workload on the different cores.  I haven't decided yet whether to
consider threaded processes differently; the E-cores are supposedly better
for threaded processes.

I also don't know if/when I'll experiment with Intel's Hardware Feedback
Interface; it will obviously depend on availability of documentation or
example code.  In theory HFI could yield quicker placement decisions.

Any additional input welcomed...

		Mike