From: Joel Fernandes <joel@joelfernandes.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
qiang.zhang@windriver.com, Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>, rcu <rcu@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] rcu: shrink each possible cpu krcp
Date: Wed, 19 Aug 2020 09:25:47 -0400 [thread overview]
Message-ID: <20200819132547.GA3875610@google.com> (raw)
In-Reply-To: <20200819112225.GA6177@pc636>
On Wed, Aug 19, 2020 at 01:22:25PM +0200, Uladzislau Rezki wrote:
> On Tue, Aug 18, 2020 at 08:04:20PM -0400, Joel Fernandes wrote:
> > On Tue, Aug 18, 2020 at 6:02 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> >
> > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > > index b8ccd7b5af82..6decb9ad2421 100644
> > > > --- a/kernel/rcu/tree.c
> > > > +++ b/kernel/rcu/tree.c
> > > > @@ -2336,10 +2336,15 @@ int rcutree_dead_cpu(unsigned int cpu)
> > > > {
> > > > struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
> > > > struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
> > > > + struct kfree_rcu_cpu *krcp;
> > > >
> > > > if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
> > > > return 0;
> > > >
> > > > + /* Drain the kcrp of this CPU. IRQs should be disabled? */
> > > > + krcp = this_cpu_ptr(&krc)
> > > > + schedule_delayed_work(&krcp->monitor_work, 0);
> > > > +
> > > >
> > > > A cpu can be offlined and its krp will be stuck until a shrinker is involved.
> > > > Maybe be never.
> > >
> > > Does the same apply to its kmalloc() per-CPU caches? If so, I have a
> > > hard time getting too worried about it. ;-)
> >
> > Looking at slab_offline_cpu() , that calls cancel_delayed_work_sync()
> > on the cache reaper who's job is to flush the per-cpu caches. So I
> > believe during CPU offlining, the per-cpu slab caches are flushed.
> >
> SLAB does it for sure, same as page allocator. There are special CPU-offline
> callbacks for both cases to perform cleanup when CPU dies.
Got it, thanks for confirming, makes sense.
thanks,
- Joel
next prev parent reply other threads:[~2020-08-19 13:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-14 6:45 [PATCH] rcu: shrink each possible cpu krcp qiang.zhang
2020-08-14 18:51 ` Uladzislau Rezki
2020-08-17 22:03 ` Joel Fernandes
2020-08-18 17:18 ` Paul E. McKenney
2020-08-18 19:00 ` Joel Fernandes
2020-08-18 21:03 ` Paul E. McKenney
2020-08-18 21:55 ` Uladzislau Rezki
2020-08-18 22:02 ` Paul E. McKenney
2020-08-19 0:04 ` Joel Fernandes
2020-08-19 3:00 ` 回复: " Zhang, Qiang
2020-08-19 13:04 ` Paul E. McKenney
2020-08-19 13:56 ` Joel Fernandes
2020-08-19 15:21 ` Paul E. McKenney
2020-08-19 15:54 ` Joel Fernandes
2020-08-19 15:58 ` Uladzislau Rezki
2020-08-20 22:39 ` Joel Fernandes
2020-08-21 15:33 ` Paul E. McKenney
2020-08-31 9:30 ` Uladzislau Rezki
2020-09-09 6:35 ` Zhang, Qiang
2020-09-09 7:03 ` RCU: Question rcu_preempt_blocked_readers_cgp in rcu_gp_fqs_loop func Zhang, Qiang
2020-09-09 11:22 ` Paul E. McKenney
2020-09-10 3:25 ` 回复: " Zhang, Qiang
2020-09-14 20:06 ` Joel Fernandes
2020-08-19 11:22 ` [PATCH] rcu: shrink each possible cpu krcp Uladzislau Rezki
2020-08-19 13:25 ` Joel Fernandes [this message]
2020-08-18 23:25 ` Joel Fernandes
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