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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Pranith Kumar <bobby.prani@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	"open list:READ-COPY UPDATE..." <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 15/16] rcu: Check for a nocb cpu before trying to spawn nocb threads
Date: Wed, 23 Jul 2014 06:42:13 -0700	[thread overview]
Message-ID: <20140723134213.GQ11241@linux.vnet.ibm.com> (raw)
In-Reply-To: <CAJhHMCDGGTtcW2ENQowKFoujLmqum8yn5ppH1RP=kv5UU+qdPw@mail.gmail.com>

On Wed, Jul 23, 2014 at 09:14:51AM -0400, Pranith Kumar wrote:
> On Wed, Jul 23, 2014 at 8:28 AM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> > On Wed, Jul 23, 2014 at 01:09:52AM -0400, Pranith Kumar wrote:
> >> This commit tries to spawn nocb kthreads only when the CPU is marked as a nocb
> >> cpu. This is a minor optimization.
> >>
> >> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
> >
> > This only happens once at boot time, so I am happier with the single check
> > at the bottom.  So sorry, but no.
> 
> Actually this happens whenever a CPU is coming online, but yes, it is
> a minor optimization for hotplug.

Fair point, but still.

                                                        Thanx, Paul

> >> ---
> >>  kernel/rcu/tree_plugin.h | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> >> index 541c776..8abff0a 100644
> >> --- a/kernel/rcu/tree_plugin.h
> >> +++ b/kernel/rcu/tree_plugin.h
> >> @@ -1490,7 +1490,8 @@ static void rcu_prepare_kthreads(int cpu)
> >>               return;
> >>
> >>       rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
> >> -     rcu_spawn_all_nocb_kthreads(cpu);
> >> +     if (rcu_is_nocb_cpu(cpu))
> >> +             rcu_spawn_all_nocb_kthreads(cpu);
> >>  }
> >>
> >>  #else /* #ifdef CONFIG_RCU_BOOST */
> >> --
> >> 2.0.0.rc2
> >>
> >
> 
> 
> 
> -- 
> Pranith
> 


  reply	other threads:[~2014-07-23 13:42 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-23  5:09 [PATCH 00/16] rcu: Some minor fixes and cleanups Pranith Kumar
2014-07-23  5:09 ` [PATCH 01/16] rcu: Use rcu_num_nodes instead of NUM_RCU_NODES Pranith Kumar
2014-07-23  5:09 ` [PATCH 02/16] rcu: Check return value for cpumask allocation Pranith Kumar
2014-07-23 12:06   ` Paul E. McKenney
2014-07-23 12:49     ` Pranith Kumar
2014-07-23 17:14     ` Pranith Kumar
2014-07-23 18:01       ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 03/16] rcu: Fix comment for gp_state field values Pranith Kumar
2014-07-23  5:09 ` [PATCH 04/16] rcu: Remove redundant check for an online CPU Pranith Kumar
2014-07-23 12:09   ` Paul E. McKenney
2014-07-23 13:23     ` Pranith Kumar
2014-07-23 13:41       ` Paul E. McKenney
2014-07-23 14:01         ` Pranith Kumar
2014-07-23 14:14           ` Paul E. McKenney
2014-07-23 15:07             ` Pranith Kumar
2014-07-23 15:21               ` Pranith Kumar
2014-07-23  5:09 ` [PATCH 05/16] rcu: Add noreturn attribute to boost kthread Pranith Kumar
2014-07-23  5:09 ` [PATCH 06/16] rcu: Clear gp_flags only when actually starting new gp Pranith Kumar
2014-07-23 12:13   ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 07/16] rcu: Save and restore irq flags in rcu_gp_cleanup() Pranith Kumar
2014-07-23 12:16   ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 08/16] rcu: Clean up rcu_spawn_one_boost_kthread() Pranith Kumar
2014-07-23  5:09 ` [PATCH 09/16] rcu: Remove redundant check for online cpu Pranith Kumar
2014-07-23 12:21   ` Paul E. McKenney
2014-07-23 12:59     ` Pranith Kumar
2014-07-23 13:50       ` Paul E. McKenney
2014-07-23 14:12         ` Pranith Kumar
2014-07-23 14:23           ` Paul E. McKenney
2014-07-23 15:11             ` Pranith Kumar
2014-07-23 15:30               ` Paul E. McKenney
2014-07-23 15:44                 ` Pranith Kumar
2014-07-23 19:15                   ` Paul E. McKenney
2014-07-23 20:01                     ` Pranith Kumar
2014-07-23 20:16                     ` Pranith Kumar
2014-07-23 20:23                       ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 10/16] rcu: Check for RCU_FLAG_GP_INIT bit in gp_flags for spurious wakeup Pranith Kumar
2014-07-23 12:23   ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 11/16] rcu: Check for spurious wakeup using return value Pranith Kumar
2014-07-23 12:26   ` Paul E. McKenney
2014-07-24  2:36     ` Pranith Kumar
2014-07-24  3:43       ` Paul E. McKenney
2014-07-24  4:03         ` Pranith Kumar
2014-07-24 18:12           ` Paul E. McKenney
2014-07-24 19:59             ` Pranith Kumar
2014-07-24 20:27               ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 12/16] rcu: Rename rcu_spawn_gp_kthread() to rcu_spawn_kthreads() Pranith Kumar
2014-07-23  5:09 ` [PATCH 13/16] rcu: Spawn nocb kthreads from rcu_prepare_kthreads() Pranith Kumar
2014-07-23  5:09 ` [PATCH 14/16] rcu: Remove redundant checks for rcu_scheduler_fully_active Pranith Kumar
2014-07-23 12:27   ` Paul E. McKenney
2014-07-23  5:09 ` [PATCH 15/16] rcu: Check for a nocb cpu before trying to spawn nocb threads Pranith Kumar
2014-07-23 12:28   ` Paul E. McKenney
2014-07-23 13:14     ` Pranith Kumar
2014-07-23 13:42       ` Paul E. McKenney [this message]
2014-07-23  5:09 ` [PATCH 16/16] rcu: kvm.sh: Fix error when you pass --cpus argument Pranith Kumar
2014-07-23 12:31   ` Paul E. McKenney
2014-07-23 14:45 ` [PATCH 00/16] rcu: Some minor fixes and cleanups Paul E. McKenney
2014-08-27  1:10   ` Pranith Kumar
2014-08-27  3:20     ` Paul E. McKenney

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