From: Joel Fernandes <joel@joelfernandes.org>
To: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: rcu@vger.kernel.org
Subject: Re: need_heavy_qs flag for PREEMPT=y kernels
Date: Mon, 12 Aug 2019 21:05:25 -0400 [thread overview]
Message-ID: <20190813010525.GB129011@google.com> (raw)
In-Reply-To: <20190813010249.GA129011@google.com>
On Mon, Aug 12, 2019 at 09:02:49PM -0400, Joel Fernandes wrote:
[snip]
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 8c494a692728..ad906d6a74fb 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -651,6 +651,12 @@ static __always_inline void rcu_nmi_exit_common(bool irq)
> > */
> > if (rdp->dynticks_nmi_nesting != 1) {
> > trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdp->dynticks);
> > + if (tick_nohz_full_cpu(rdp->cpu) &&
> > + rdp->dynticks_nmi_nesting == 2 &&
> > + rdp->rcu_urgent_qs && !rdp->rcu_forced_tick) {
> > + rdp->rcu_forced_tick = true;
> > + tick_dep_set_cpu(rdp->cpu, TICK_DEP_MASK_RCU);
> > + }
>
>
> Instead of checking dynticks_nmi_nesting == 2 in rcu_nmi_exit_common(), can
> we do the tick_dep_set_cpu(rdp->cpu, TICK_DEP_MASK_RCU) from
> rcu_nmi_enter_common() ? We could add this code there, under the "if
> (rcu_dynticks_curr_cpu_in_eqs())".
Actually, the other way. if (!rcu_dynticks_curr_cpu_in_eqs()) then do the
tick_dep_set_cpu().
thanks,
- Joel
next prev parent reply other threads:[~2019-08-13 1:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-11 18:08 need_heavy_qs flag for PREEMPT=y kernels Joel Fernandes
2019-08-11 18:34 ` Joel Fernandes
2019-08-11 21:16 ` Paul E. McKenney
2019-08-11 21:25 ` Joel Fernandes
2019-08-11 23:30 ` Paul E. McKenney
2019-08-12 1:24 ` Joel Fernandes
2019-08-12 1:40 ` Joel Fernandes
2019-08-12 3:57 ` Paul E. McKenney
2019-08-11 21:13 ` Paul E. McKenney
2019-08-12 3:21 ` Joel Fernandes
2019-08-12 3:53 ` Paul E. McKenney
2019-08-12 21:20 ` Joel Fernandes
2019-08-12 23:01 ` Paul E. McKenney
2019-08-13 1:02 ` Joel Fernandes
2019-08-13 1:05 ` Joel Fernandes [this message]
2019-08-13 2:28 ` Paul E. McKenney
2019-08-13 2:27 ` Paul E. McKenney
2019-08-13 2:50 ` Paul E. McKenney
2019-08-15 17:17 ` Paul E. McKenney
2019-08-15 20:04 ` Joel Fernandes
2019-08-15 20:31 ` Paul E. McKenney
2019-08-15 21:22 ` Joel Fernandes
2019-08-15 21:27 ` Joel Fernandes
2019-08-15 21:34 ` Joel Fernandes
2019-08-15 21:57 ` Paul E. McKenney
2019-08-15 21:45 ` Paul E. McKenney
2019-08-16 0:02 ` Joel Fernandes
2019-08-19 12:34 ` Frederic Weisbecker
2019-08-19 12:09 ` Frederic Weisbecker
2019-08-19 16:57 ` Frederic Weisbecker
2019-08-19 22:31 ` Paul E. McKenney
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