From: "Paul E. McKenney" <paulmck@kernel.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
rushikesh.s.kadam@intel.com, urezki@gmail.com,
neeraj.iitr10@gmail.com, rostedt@goodmis.org,
youssefesmat@google.com, surenb@google.com
Subject: Re: [PATCH v8 02/13] rcu: Make call_rcu() lazy to save power
Date: Fri, 14 Oct 2022 08:45:47 -0700 [thread overview]
Message-ID: <20221014154547.GA710792@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <CAEXW_YSsEQ8krr9ckCOmO1B=C+Oy+8j_BtetQeNu1McH5nSuQg@mail.gmail.com>
On Wed, Oct 12, 2022 at 03:54:25PM -0400, Joel Fernandes wrote:
> On Tue, Oct 11, 2022 at 7:10 PM Frederic Weisbecker <frederic@kernel.org> wrote:
> >
> > On Tue, Oct 11, 2022 at 06:01:31PM +0000, Joel Fernandes (Google) wrote:
> > > @@ -269,10 +294,14 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype,
> > > raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
> > >
> > > /*
> > > - * Bypass wakeup overrides previous deferments. In case
> > > - * of callback storm, no need to wake up too early.
> > > + * Bypass wakeup overrides previous deferments. In case of
> > > + * callback storm, no need to wake up too early.
> > > */
> > > - if (waketype == RCU_NOCB_WAKE_BYPASS) {
> > > + if (waketype == RCU_NOCB_WAKE_LAZY &&
> > > + READ_ONCE(rdp->nocb_defer_wakeup) == RCU_NOCB_WAKE_NOT) {
> >
> > No need for READ_ONCE() here.
> >
> > > + mod_timer(&rdp_gp->nocb_timer, jiffies + jiffies_till_flush);
> > > + WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
> > > + } else if (waketype == RCU_NOCB_WAKE_BYPASS) {
> > > mod_timer(&rdp_gp->nocb_timer, jiffies + 2);
> > > WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
> > > } else {
> > > @@ -611,6 +682,8 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
> > > unsigned long flags;
> > > bool gotcbs = false;
> > > unsigned long j = jiffies;
> > > + bool lazy = false;
> > > + long lazy_ncbs;
> >
> > Looks like lazy_ncbs can be declared withing the loop, as well as bypass_cbs.
> >
> > Anyway, apart from such boring cosmectics:
> >
> > Acked-by: Frederic Weisbecker <frederic@kernel.org>
>
> Thanks, I folded the cosmetic suggestions with the Ack and pushed it to:
> https://github.com/joelagnel/linux-kernel.git (branch rcu-next-oct.12.22)
Just following back up with Frederic to see if all of your guys' words
had the same meanings. ;-)
Thanx, Paul
next prev parent reply other threads:[~2022-10-14 15:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-11 18:01 [PATCH v8 00/13] rcu: call_rcu() power improvements Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 01/13] rcu: Fix missing nocb gp wake on rcu_barrier() Joel Fernandes (Google)
2022-10-14 14:21 ` Paul E. McKenney
2022-10-14 14:40 ` Frederic Weisbecker
2022-10-14 15:03 ` Paul E. McKenney
2022-10-14 15:19 ` Joel Fernandes
2022-10-14 15:46 ` Paul E. McKenney
2022-10-14 20:47 ` Frederic Weisbecker
2022-10-16 15:16 ` Paul E. McKenney
2022-10-16 15:56 ` Joel Fernandes
2022-10-11 18:01 ` [PATCH v8 02/13] rcu: Make call_rcu() lazy to save power Joel Fernandes (Google)
2022-10-11 23:10 ` Frederic Weisbecker
2022-10-12 19:54 ` Joel Fernandes
2022-10-14 15:45 ` Paul E. McKenney [this message]
2022-10-11 18:01 ` [PATCH v8 03/13] rcu: Refactor code a bit in rcu_nocb_do_flush_bypass() Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 04/13] rcu: shrinker for lazy rcu Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 05/13] rcuscale: Add laziness and kfree tests Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 06/13] percpu-refcount: Use call_rcu_flush() for atomic switch Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 07/13] rcu/sync: Use call_rcu_flush() instead of call_rcu Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 08/13] rcu/rcuscale: Use call_rcu_flush() for async reader test Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 09/13] rcu/rcutorture: Use call_rcu_flush() where needed Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 10/13] scsi/scsi_error: Use call_rcu_flush() instead of call_rcu() Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 11/13] workqueue: Make queue_rcu_work() use call_rcu_flush() Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 12/13] rxrpc: Use call_rcu_flush() instead of call_rcu() Joel Fernandes (Google)
2022-10-11 18:01 ` [PATCH v8 13/13] rcu/debug: Add wake-up debugging for lazy callbacks Joel Fernandes (Google)
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