On Tue, Jun 30, 2015 at 02:48:30PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
This seems like a good place to explain why this is a desirable thing,
no?
Why would you want to limit this?
> Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> ---
> kernel/rcu/tree.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 308b6acb4260..247aa1120c4c 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3505,10 +3505,19 @@ void synchronize_sched_expedited(void)
> !atomic_read(&rsp->expedited_need_qs));
>
> rcu_exp_gp_seq_end(rsp);
> - mutex_unlock(&rnp->exp_funnel_mutex);
> smp_mb(); /* ensure subsequent action seen after grace period. */
> - if (rsp->gp_kthread && rcu_gp_in_progress(rsp))
> - wake_up(&rsp->gp_wq);
> + if (rsp->gp_kthread && rcu_gp_in_progress(rsp)) {
> + static unsigned long nextgp;
> + static unsigned long nextjiffy;
> +
> + if (time_after_eq(jiffies, nextgp) ||
> + ULONG_CMP_GE(rsp->gpnum, nextgp)) {
> + nextgp = rsp->gpnum + 4;
> + nextjiffy = jiffies + 10;
> + wake_up(&rsp->gp_wq);
> + }
> + }
> + mutex_unlock(&rnp->exp_funnel_mutex);
>
> put_online_cpus();
> }
> --
> 1.8.1.5
>
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