Re: Interesting scheduling times

Larry McVoy (lm@bitmover.com)
Tue, 22 Sep 1998 09:24:07 -0600


: If you (or I or anybody else) doesn't understand it either, then we
: should just say say so (or say nothing) and then be quiet. Telling
: Richard over and over that his benchmark is wrong isn't doing anything
: to either get him to completely rethink his design or answer the
: question of where the variance comes from. If the variance comes from
: a bad design in his test, it ought to be possible to state what is
: wrong. People have tried to do that, and Richard has, to my mind,
: offered at least a reasonable defense of what he's trying to do. If
: you can't explain his error to him so that he can see it, then just
: stop trying. I have to say that nobody so far, not Linus, not David
: Miller, not Larry McVoy, have explained his design error in a way that
: makes it clear to me, at least.

The problems with this argument are:

. We've pointed him at a benchmark that doesn't have the same problems.

. We've tried to explain that he's counting angels on the head of a pin,
that what he is doing is not relevant and certainly would not be taken
as justification for a scheduler redesign, which seems to be his goal.

. His defense is completely unreasonable, both from a statistical
point of view (consider his standard deviation) and from a systems
architecture point of view.

. While it would be nice for Richard if someone dissected his benchmark,
the people who can have already pruned that branch of the tree as
uninteresting, i.e., no payoff. There are a million uninteresting
things to look at - a good kernel hack quickly sorts out which ones
are worthwhile. It costs time and effort to explain the wrong paths,
using that time takes away from causes that are actually worthwhile.

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