Re: [PATCH RFC tip/core/rcu] Add callback-free CPUs

From: Peter Zijlstra
Date: Thu Sep 06 2012 - 14:22:08 EST


On Thu, 2012-09-06 at 10:46 -0700, Paul E. McKenney wrote:
> Getting these
> CPUs into adaptive-tick mode more quickly reduces OS jitter, which is
> one big expected benefit of adaptive-tick mode.

I'm not sure I agree with that statement. Its a transition thing and
therefore statistically irrelevant on the whole -- assuming we
transition rarely.

And for those who cannot deal with the transition effects, a barrier was
proposed which would wait until the system hit this state -- although
the specific implementation of this isn't clear yet afaik.

I very much think we should focus on getting adaptive tick working as
simple as possible and worry about transition effects later, if at all.
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