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From:   Valentin Schneider <valentin.schneider@arm.com>
To:     Frederic Weisbecker <frederic@kernel.org>,
        "Paul E . McKenney" <paulmck@kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        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 09/11] rcu: Fix callbacks processing time limit retaining cond_resched()
In-Reply-To: <20210929221012.228270-10-frederic@kernel.org>
References: <20210929221012.228270-1-frederic@kernel.org> <20210929221012.228270-10-frederic@kernel.org>
Date:   Fri, 01 Oct 2021 18:51:21 +0100
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On 30/09/21 00:10, Frederic Weisbecker wrote:
> The callbacks processing time limit makes sure we are not exceeding a
> given amount of time executing the queue.
>
> However its "continue" clause bypasses the cond_resched() call on
> rcuc and NOCB kthreads, delaying it until we reach the limit, which can
> be very long...
>
> Make sure the scheduler has a higher priority than the time limit.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Cc: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Joel Fernandes <joel@joelfernandes.org>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
> Cc: Uladzislau Rezki <urezki@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>

Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>