From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: rcu@vger.kernel.org
Subject: Re: need_heavy_qs flag for PREEMPT=y kernels
Date: Mon, 12 Aug 2019 19:50:57 -0700 [thread overview]
Message-ID: <20190813025057.GY28441@linux.ibm.com> (raw)
In-Reply-To: <20190813022726.GW28441@linux.ibm.com>
On Mon, Aug 12, 2019 at 07:27:26PM -0700, Paul E. McKenney wrote:
> On Mon, Aug 12, 2019 at 09:02:49PM -0400, Joel Fernandes wrote:
> > On Mon, Aug 12, 2019 at 04:01:38PM -0700, Paul E. McKenney wrote:
[ . . . ]
> > 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())".
>
> It might well make sense to do this on entry, especially if doing so
> might safe an instruction or two. It won't make the tick happen much
> faster, given that interrupts are disabled throughout the handler.
>
> > I will test this patch tomorrow and let you know how it goes.
>
> No need, it dies horribly and quickly with rcutorture. Not exactly
> a surprise. ;-)
And also not a surprise, due to a laughably stupid mistake...
Thanx, Paul
next prev parent reply other threads:[~2019-08-13 2:51 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
2019-08-13 2:28 ` Paul E. McKenney
2019-08-13 2:27 ` Paul E. McKenney
2019-08-13 2:50 ` Paul E. McKenney [this message]
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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