It's because Linus wants it that way, with a view to encouraging the
development of algorithms that work well across a broad range of
configurations without requiring a lot of tuning. So it's a case of short
term pain for long term gain.
Keep in mind that once you start exposing tuning parameters you tend to get
lots of user programs out there that break without the parameters, or if the
parameters don't behave the same way across versions. Official tuning
parameters also get in the way of trying out new algorithms, which might not
even support the old tweaks, for example.
> I would like to be able to set up a test system in my laboratory, fire up a
> benchmark that emulates a real-world workload and tweak these parameters
> somewhere in /proc in real time, while watching the response times of my
> benchmark transactions. I can do this in Tru64, I can do this in a number of
> other operating systems. Right now, for all practical purposes, when I want
> to perform an experiment like this, I need to recompile, quite often, the
> *entire* kernel, reboot and re-run my benchmark. In other words, if the
> parameters were tunable, what now takes *days* to do could be accomplished
> in hours, even minutes, with just a little up-front work.
So then you probably just want to grab one of the many patches that expose
things through proc and use it as a jumping-off point to expose your own
tweaks. As you say, much faster than recompiling every time.
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