Re: [PATCH 15/16] rcu: Check for a nocb cpu before trying to spawn nocb threads

Paul E. McKenney
2014-07-23T12:28:56Z

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.

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
>