automatic installation of PAE-enabled kernel?

[D. Hugh Redelmeier]

| From: Robert P. J. Day <rpjday at crashcourse.ca>

| maybe someone more knowledgeable can clarify this.  and, again, i'm
| still unsure if there's any harm in running a PAE-enabled kernel even
| when you don't need one.

There would only be one kernel if supporting PAE didn't have a cost.
There is probably a cost in code size and in code pathlength.

I found this datapoint:
http://linux-memhotadd.sourceforge.net/hotadd.html

    "Benchmarks seem to indicate around 3-6% CPU hit just for using
    the PAE extensions (ie. it applies regardless of whether you are
    actually accessing memory locations greater then 4GB)."

I don't know if it is reliable -- read the paper and you judge.

I would guess that the real CPU time cost is some linear combination of the
number of system calls, interrupts, and process switches.  For
example, a system with only CPU-intensive applications might not be
hit. Now that I read more of the paper, that seems to be confirmed --
see 6.1.1.