Re: [PATCH tip/core/rcu 0/5] Fix for cond_resched performance regression

[josh]

On Fri, Jun 20, 2014 at 12:12:36PM -0700, Paul E. McKenney wrote:
> o	Make cond_resched() a no-op for PREEMPT=y.  This might well turn
> 	out to be a good thing, but it doesn't help give RCU the quiescent
> 	states that it needs.

What about doing this, together with letting the fqs logic poke
un-quiesced kernel code as needed?  That way, rather than having
cond_resched do any work, you have the fqs logic recognize that a
particular CPU has gone too long without quiescing, without disturbing
that CPU at all if it hasn't gone too long.

- Josh Triplett
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