Re: [PATCH RFC tip/core/rcu] Parallelize and economize NOCB kthread wakeups

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Wed, Jul 02, 2014 at 07:26:00PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 02, 2014 at 10:08:38AM -0700, Paul E. McKenney wrote:
> > As were others, not that long ago.  Today is the first hint that I got
> > that you feel otherwise.  But it does look like the softirq approach to
> > callback processing needs to stick around for awhile longer.  Nice to
> > hear that softirq is now "sane and normal" again, I guess.  ;-)
> 
> Nah, softirqs are still totally annoying :-)

Name me one thing that isn't annoying.  ;-)

> So I've lost detail again, but it seems to me that on all CPUs that are
> actually getting ticks, waking tasks to process the RCU state is
> entirely over doing it. Might as well keep processing their RCU state
> from the tick as was previously done.

And that is in fact the approach taken by my patch.  For which I just
kicked off testing, so expect an update later today.  (And that -is-
optimistic!  A pessimistic viewpoint would hold that the patch would
turn out to be so broken that it would take -weeks- to get a fix!)

							Thanx, Paul