From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Valentin Schneider <Valentin.Schneider@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Uladzislau Rezki <urezki@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Boqun Feng <boqun.feng@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Josh Triplett <josh@joshtriplett.org>,
Joel Fernandes <joel@joelfernandes.org>,
rcu@vger.kernel.org
Subject: Re: [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT_RT with NOCB + a few other fixes v2
Date: Wed, 13 Oct 2021 12:01:29 +0200 [thread overview]
Message-ID: <20211013100129.GA377556@lothringen> (raw)
In-Reply-To: <20211013032832.GQ880162@paulmck-ThinkPad-P17-Gen-1>
On Tue, Oct 12, 2021 at 08:28:32PM -0700, Paul E. McKenney wrote:
> On Tue, Oct 12, 2021 at 05:32:15PM -0700, Paul E. McKenney wrote:
> > On Mon, Oct 11, 2021 at 04:51:29PM +0200, Frederic Weisbecker wrote:
> > > Hi,
> > >
> > > No code change in this v2, only changelogs:
> > >
> > > * Add tags from Valentin and Sebastian
> > >
> > > * Remove last reference to SEGCBLIST_SOFTIRQ_ONLY (thanks Valentin)
> > >
> > > * Rewrite changelog for "rcu/nocb: Check a stable offloaded state to manipulate qlen_last_fqs_check"
> > > after off-list debates with Paul.
> > >
> > > * Remove the scenario with softirq interrupting rcuc on
> > > "rcu/nocb: Limit number of softirq callbacks only on softirq" as it's
> > > probably not possible (thanks Valentin).
> > >
> > > * Remove the scenario with task spent scheduling out accounted on tlimit
> > > as it's not possible (thanks Valentin)
> > > (see "rcu: Apply callbacks processing time limit only on softirq")
> > >
> > > * Fixed changelog of
> > > "rcu/nocb: Don't invoke local rcu core on callback overload from nocb kthread"
> > > (thanks Sebastian).
> > >
> > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> > > rcu/rt-v2
> > >
> > > HEAD: 2c9349986d5f70a555195139665841cd98e9aba4
> > >
> > > Thanks,
> > > Frederic
> >
> > Nice!
> >
> > I queued these for further review and testing. I reworked the commit log
> > of 6/11 to give my idea of the reason, though I freely admit that this
> > reason is not as compelling as it no doubt seemed when I wrote that code.
>
> But in initial tests TREE04.5, TREE04.6, and TREE04.9 all hit the
> WARN_ON(1) in rcu_torture_barrier(), which indicates rcu_barrier()
> breakage. My best (but not so good) guess is a five-hour MTBF on a
> dual-socket system.
>
> I started an automated "git bisect" with each step running 100 hours
> of TREE04, but I would be surprised if anything useful comes of it.
> Pleased, mind you, but surprised.
Oops, trying those scenario on my side as well.
Thanks!
next prev parent reply other threads:[~2021-10-13 10:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 14:51 [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT_RT with NOCB + a few other fixes v2 Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 01/11] rcu/nocb: Make local rcu_nocb_lock_irqsave() safe against concurrent deoffloading Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 02/11] rcu/nocb: Prepare state machine for a new step Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 03/11] rcu/nocb: Invoke rcu_core() at the start of deoffloading Frederic Weisbecker
2021-10-13 16:07 ` Boqun Feng
2021-10-14 11:07 ` Frederic Weisbecker
2021-10-14 11:42 ` Valentin Schneider
2021-10-14 13:57 ` Boqun Feng
2021-10-11 14:51 ` [PATCH 04/11] rcu/nocb: Make rcu_core() callbacks acceleration preempt-safe Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 05/11] rcu/nocb: Make rcu_core() callbacks acceleration (de-)offloading safe Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 06/11] rcu/nocb: Check a stable offloaded state to manipulate qlen_last_fqs_check Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 07/11] rcu/nocb: Use appropriate rcu_nocb_lock_irqsave() Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 08/11] rcu/nocb: Limit number of softirq callbacks only on softirq Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 09/11] rcu: Fix callbacks processing time limit retaining cond_resched() Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 10/11] rcu: Apply callbacks processing time limit only on softirq Frederic Weisbecker
2021-10-11 14:51 ` [PATCH 11/11] rcu/nocb: Don't invoke local rcu core on callback overload from nocb kthread Frederic Weisbecker
2021-10-13 0:32 ` [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT_RT with NOCB + a few other fixes v2 Paul E. McKenney
2021-10-13 3:28 ` Paul E. McKenney
2021-10-13 10:01 ` Frederic Weisbecker [this message]
2021-10-13 11:43 ` Frederic Weisbecker
2021-10-13 16:27 ` Paul E. McKenney
2021-10-14 10:43 ` Frederic Weisbecker
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