Here's a kooky idea...
I'm not sure about this detail, but I would guess that the int
schedulers are trying to determine relatively stable priority values for
processes. A process does not instantly come to its correct priority
level, because it gets there based on accumulation of behavioral patterns.
Well, it occurs to me that we could benefit from situations where
priority changes are underdamped. The results would sometimes be an
oscillation in priority levels. In the short term, a given process may
be given different amounts of CPU time when it is run, although in the
long term, it should average out.
At the same time, certain tasks can only be judged correctly over the
long term, like X, for example. Its long-term behavior is interactive,
but now and then, it will become a CPU hog, and we want to LET it.
The idea I'm proposing, however poorly formed, is that if we allow some
"excessive" oscillation early on in the life of a process, we may be
able to more quickly get processes to NEAR its correct priority, OR get
its CPU time over the course of three times being run for the
underdamped case to be about the same as it would be if we knew in
advance what the priority should be. But in the underdamped case, the
priority would continue to oscillate up and down around the correct
level, because we are intentionally overshooting the mark each time we
adjust priority.
This may not be related, but something that pops into my mind is a
numerical method called Newton's Method. It's a way to solve for roots
of an equation, and it involved derivatives, and I don't quite remember
how it works. But in any event, the results are less accurate than,
say, bisection, but you get to the answer MUCH more quickly.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Aug 07 2003 - 22:00:34 EST