Re: [PATCH 05/32] nohz: Move rcu dynticks idle mode handling to idle enter/exit APIs

Peter Zijlstra
2011-08-29T14:25:46Z

On Mon, 2011-08-15 at 17:52 +0200, Frederic Weisbecker wrote:
> To prepare for nohz / idle logic split, pull out the rcu dynticks
> idle mode switching to strict idle entry/exit areas.
>
> So we make the dyntick mode possible without always involving rcu
> extended quiescent state.

Why is this a good thing? I would be thinking that if we're a userspace
bound task and we disable the tick rcu would be finished on this cpu and
thus the extended quiescent state is just what we want?