From: Frederic Weisbecker <frederic@kernel.org>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org,
Josh Triplett <josh@joshtriplett.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH rcu/next 3/3] rcu: Fix late wakeup when flush of bypass cblist happens
Date: Fri, 16 Sep 2022 14:51:39 +0200 [thread overview]
Message-ID: <20220916125139.GA25891@lothringen> (raw)
In-Reply-To: <20220915001419.55617-4-joel@joelfernandes.org>
On Thu, Sep 15, 2022 at 12:14:19AM +0000, Joel Fernandes (Google) wrote:
> When the bypass cblist gets too big or its timeout has occurred, it is
> flushed into the main cblist. However, the bypass timer is still running
> and the behavior is that it would eventually expire and wake the GP
> thread.
>
> Since we are going to use the bypass cblist for lazy CBs, do the wakeup
> soon as the flush happens. Otherwise, the lazy-timer will go off much
> later and the now-non-lazy cblist CBs can get stranded for the duration
> of the timer.
>
> This is a good thing to do anyway, since it makes the behavior consistent with
> behavior of other code paths where queueing something into the ->cblist makes
> the GP kthread in a non-sleeping state quickly.
>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
prev parent reply other threads:[~2022-09-16 12:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-15 0:14 [PATCH rcu/next 0/3] Preparatory patches borrowed from lazy rcu v5 Joel Fernandes (Google)
2022-09-15 0:14 ` [PATCH rcu/next 1/3] rcu/tree: Use READ_ONCE() for lockless read of rnp->qsmask Joel Fernandes (Google)
2022-09-16 10:55 ` Frederic Weisbecker
2022-09-15 0:14 ` [PATCH rcu/next 2/3] rcu: Move trace_rcu_callback() before bypassing Joel Fernandes (Google)
2022-09-16 11:09 ` Frederic Weisbecker
2022-09-16 14:10 ` Joel Fernandes
2022-09-16 14:14 ` Joel Fernandes
2022-09-16 22:19 ` Joel Fernandes
2022-09-16 22:21 ` Joel Fernandes
2022-09-15 0:14 ` [PATCH rcu/next 3/3] rcu: Fix late wakeup when flush of bypass cblist happens Joel Fernandes (Google)
2022-09-16 12:51 ` Frederic Weisbecker [this message]
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