Re: [PATCH 12/13] rcu/nocb: Prepare for finegrained deferred wakeup
On Tue, Mar 16, 2021 at 12:45:26PM +0100, Frederic Weisbecker wrote: > On Mon, Mar 15, 2021 at 08:02:39PM -0700, Paul E. McKenney wrote: > > On Tue, Feb 23, 2021 at 01:10:10AM +0100, Frederic Weisbecker wrote: > > > Provide a way to tune the deferred wakeup level we want to perform from > > > a safe wakeup point. Currently those sites are: > > > > > > * nocb_timer > > > * user/idle/guest entry > > > * CPU down > > > * softirq/rcuc > > > > > > All of these sites perform the wake up for both RCU_NOCB_WAKE and > > > RCU_NOCB_WAKE_FORCE. > > > > > > In order to merge nocb_timer and nocb_bypass_timer together, we plan to > > > add a new RCU_NOCB_WAKE_BYPASS that really want to be deferred until > > > a timer fires so that we don't wake up the NOCB-gp kthread too early. > > > > > > To prepare for that, integrate a wake up level/limit that a callsite is > > > deemed to perform. > > > > This appears to need the following in order to build for non-NOCB > > configurations. I will fold it in and am retesting. > > > > Thanx, Paul > > > > > > > > commit 55f59dd75a11455cf558fd387fbf9011017dcc8a > > Author: Paul E. McKenney > > Date: Mon Mar 15 20:00:34 2021 -0700 > > > > squash! rcu/nocb: Prepare for fine-grained deferred wakeup > > > > [ paulmck: Fix non-NOCB rcu_nocb_need_deferred_wakeup() definition. ] > > Signed-off-by: Paul E. McKenney > > > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > > index 0cc7f68..dfb048e 100644 > > --- a/kernel/rcu/tree_plugin.h > > +++ b/kernel/rcu/tree_plugin.h > > @@ -2926,7 +2926,7 @@ static void __init > > rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp) > > { > > } > > > > -static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp) > > +static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level) > > { > > return false; > > } > > Oops thanks, I missed that. And with this, light rcutorture testing passed. I hope to pound on it harder later this week. Thanx, Paul
Re: [PATCH 12/13] rcu/nocb: Prepare for finegrained deferred wakeup
On Mon, Mar 15, 2021 at 08:02:39PM -0700, Paul E. McKenney wrote: > On Tue, Feb 23, 2021 at 01:10:10AM +0100, Frederic Weisbecker wrote: > > Provide a way to tune the deferred wakeup level we want to perform from > > a safe wakeup point. Currently those sites are: > > > > * nocb_timer > > * user/idle/guest entry > > * CPU down > > * softirq/rcuc > > > > All of these sites perform the wake up for both RCU_NOCB_WAKE and > > RCU_NOCB_WAKE_FORCE. > > > > In order to merge nocb_timer and nocb_bypass_timer together, we plan to > > add a new RCU_NOCB_WAKE_BYPASS that really want to be deferred until > > a timer fires so that we don't wake up the NOCB-gp kthread too early. > > > > To prepare for that, integrate a wake up level/limit that a callsite is > > deemed to perform. > > This appears to need the following in order to build for non-NOCB > configurations. I will fold it in and am retesting. > > Thanx, Paul > > > > commit 55f59dd75a11455cf558fd387fbf9011017dcc8a > Author: Paul E. McKenney > Date: Mon Mar 15 20:00:34 2021 -0700 > > squash! rcu/nocb: Prepare for fine-grained deferred wakeup > > [ paulmck: Fix non-NOCB rcu_nocb_need_deferred_wakeup() definition. ] > Signed-off-by: Paul E. McKenney > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 0cc7f68..dfb048e 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -2926,7 +2926,7 @@ static void __init > rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp) > { > } > > -static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp) > +static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level) > { > return false; > } Oops thanks, I missed that.
Re: [PATCH 12/13] rcu/nocb: Prepare for finegrained deferred wakeup
On Tue, Feb 23, 2021 at 01:10:10AM +0100, Frederic Weisbecker wrote: > Provide a way to tune the deferred wakeup level we want to perform from > a safe wakeup point. Currently those sites are: > > * nocb_timer > * user/idle/guest entry > * CPU down > * softirq/rcuc > > All of these sites perform the wake up for both RCU_NOCB_WAKE and > RCU_NOCB_WAKE_FORCE. > > In order to merge nocb_timer and nocb_bypass_timer together, we plan to > add a new RCU_NOCB_WAKE_BYPASS that really want to be deferred until > a timer fires so that we don't wake up the NOCB-gp kthread too early. > > To prepare for that, integrate a wake up level/limit that a callsite is > deemed to perform. This appears to need the following in order to build for non-NOCB configurations. I will fold it in and am retesting. Thanx, Paul commit 55f59dd75a11455cf558fd387fbf9011017dcc8a Author: Paul E. McKenney Date: Mon Mar 15 20:00:34 2021 -0700 squash! rcu/nocb: Prepare for fine-grained deferred wakeup [ paulmck: Fix non-NOCB rcu_nocb_need_deferred_wakeup() definition. ] Signed-off-by: Paul E. McKenney diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 0cc7f68..dfb048e 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2926,7 +2926,7 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp) { } -static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp) +static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp, int level) { return false; }