Re: [RFC][PATCH 12/13] stop_machine: Remove lglock

[Peter Zijlstra]

On Wed, Jun 24, 2015 at 08:27:19AM -0700, Paul E. McKenney wrote:
> > The thing is, if we're stalled on a stop_one_cpu() call, the sync_rcu()
> > is equally stalled. The sync_rcu() cannot wait more efficient than we're
> > already waiting either.
> 
> Ah, but synchronize_rcu() doesn't force waiting on more than one extra
> grace period.  With strictly queued mutex, you can end up waiting on
> several.

But you could fix that by replacing/augmenting the expedited ticket with
gpnum/copmleted as used in get_state_synchronize_rcu()/cond_synchronize_rcu().


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