Re: need_heavy_qs flag for PREEMPT=y kernels

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

On Mon, Aug 19, 2019 at 06:57:10PM +0200, Frederic Weisbecker wrote:
> On Thu, Aug 15, 2019 at 01:31:07PM -0700, Paul E. McKenney wrote:
> > On Thu, Aug 15, 2019 at 04:04:32PM -0400, Joel Fernandes wrote:
> > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> > > index be9707f68024..e697c7a2ce67 100644
> > > --- a/kernel/time/tick-sched.c
> > > +++ b/kernel/time/tick-sched.c
> > > @@ -198,6 +198,10 @@ static bool check_tick_dependency(atomic_t *dep)
> > >  		return true;
> > >  	}
> > >  
> > > +	if (val & TICK_DEP_MASK_CLOCK_RCU) {
> > > +		return true;
> > > +	}
> > > +
> > >  	return false;
> > >  }
> > 
> > That one is not in my tree, either.  Frederic, should I add this to
> > your patch?  For that matter, may I add your Signed-off-by as well?
> > Your original is in my -rcu tree at:
> > 
> > 0cb41806c799 ("EXP nohz: Add TICK_DEP_BIT_RCU")
> > 
> > I am testing Joel's suggested addition now.
> 
> Also this:

Good point, added!

							Thanx, Paul

> diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
> index b7a904825e7d..295517f109d7 100644
> --- a/include/trace/events/timer.h
> +++ b/include/trace/events/timer.h
> @@ -367,7 +367,8 @@ TRACE_EVENT(itimer_expire,
>  		tick_dep_name(POSIX_TIMER)		\
>  		tick_dep_name(PERF_EVENTS)		\
>  		tick_dep_name(SCHED)			\
> -		tick_dep_name_end(CLOCK_UNSTABLE)
> +		tick_dep_name(CLOCK_UNSTABLE)		\
> +		tick_dep_name_end(RCU)
>  
>  #undef tick_dep_name
>  #undef tick_dep_mask_name
>