Re: [PATCH v2 tip/core/rcu 0/13] Miscellaneous fixes for 4.12

[Peter Zijlstra]

On Wed, Apr 19, 2017 at 07:47:30AM -0700, Paul E. McKenney wrote:
> The RCU expedited primitives have been completely rewritten since then,
> and no longer use try_stop_cpus(), no longer disturb idle CPUs, and no
> longer disturb nohz_full CPUs running in userspace.  In addition, there
> is the rcupdate.rcu_normal kernel boot paramter for those who want to
> completely avoid RCU expedited primitives.
> 
> So it seems to me to be time for the patch below.  Thoughts?

So I forgot all the details again; but if I'm not mistaken it still
prods CPUs with IPIs (just not idle/nohz_full CPUs). So its still not
ideal to sprinkle them around.

Which would still argue against using them too much.