Re: [PATCH] a local-timer-free version of RCU

[Frederic Weisbecker <fweisbec@gmail.com>]

On Wed, Nov 10, 2010 at 08:19:20PM -0800, Paul E. McKenney wrote:
> On Wed, Nov 10, 2010 at 06:31:11PM +0100, Peter Zijlstra wrote:
> > On Wed, 2010-11-10 at 16:54 +0100, Frederic Weisbecker wrote:
> > > run the sched tick and if there was nothing to do
> > > for some time and we are in userspace, deactivate it. 
> > 
> > Not for some time, immediately, have the tick track if it was useful, if
> > it was not, have it stop itself, like:
> > 
> > tick()
> > {
> >  int stop = 1;
> > 
> >  if (nr_running > 1)
> >   stop = 0;
> > 
> >  if(rcu_needs_cpu())
> >   stop = 0;
> > 
> >  ...
> > 
> > 
> >  if (stop)
> >   enter_nohz_mode();
> > }
> 
> I am still holding out for a dyntick-hpc version of RCU that does not
> need the tick.  ;-)


So you don't think it would be an appropriate solution? Keeping the tick for short
periods of time while we need it only, that looks quite a good way to try.

Hmm?