[ltt-dev] [PATCH 5/7] urcu, call_rcu: avoid create call_rcu_data for child when unneed

[Paul E. McKenney]

On Wed, Sep 28, 2011 at 04:34:31PM +0800, Lai Jiangshan wrote:
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>

Nice optimization!!!

Reviewed-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>

> ---
>  urcu-call-rcu-impl.h |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h
> index 87d9157..65c1c7a 100644
> --- a/urcu-call-rcu-impl.h
> +++ b/urcu-call-rcu-impl.h
> @@ -675,6 +675,10 @@ void call_rcu_after_fork_child(void)
>  	/* Release the mutex. */
>  	call_rcu_unlock(&call_rcu_mutex);
> 
> +	/* Do nothing when call_rcu() has not been used */
> +	if (cds_list_empty(&call_rcu_data_list))
> +		return;
> +
>  	/*
>  	 * Allocate a new default call_rcu_data structure in order
>  	 * to get a working call_rcu thread to go with it.
> -- 
> 1.7.4.4
>