On 19/01/16 17:50, Mark Brown wrote:

On Tue, Jan 19, 2016 at 04:05:51PM +0100, Peter Zijlstra wrote:

quoted

On Fri, Jan 08, 2016 at 02:09:28PM +0000, Juri Lelli wrote:

quoted

quoted

    cons: - not easy to come up with a clean solution, as it seems interaction
            with several subsystems (e.g., cpufreq) is required
          - not easy to agree upon a single benchmark (that has to be both
            representative and simple enough to run at boot)
          - numbers might (and do) vary from boot to boot

quoted

This last point is a total pain for benchmarking, it means nothing is
every reproducible.

quoted

Therefore, I would always augment the above (2) with the below (3), such
that you can overwrite the results with a known stable set of numbers:

The suggestion when the previous version was being discussed was that
there are supposed to be some other knobs one uses for tuning and one
was never supposed to use these numbers.

Right, DT solution might live without a sysfs interface, as you want to
use those other knobs for runtime tuning. Dynamic solution instead, and
I think this is what Peter was also pointing out, will most probably
require a sysfs interface for cases in which variation of default values
from boot to boot is not acceptable.