[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 5 May 2011 17:31:35 +0800
From: Yong Zhang <yong.zhang0@...il.com>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
dipankar@...ibm.com, akpm@...ux-foundation.org,
mathieu.desnoyers@...ymtl.ca, josh@...htriplett.org,
niv@...ibm.com, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, Valdis.Kletnieks@...edu, dhowells@...hat.com,
eric.dumazet@...il.com, darren@...art.com, patches@...aro.org,
"Paul E. McKenney" <paul.mckenney@...aro.org>
Subject: Re: [PATCH tip/core/rcu 05/86] rcu: move TREE_RCU from softirq to kthread
On Sun, May 1, 2011 at 9:20 PM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
> From: Paul E. McKenney <paul.mckenney@...aro.org>
>
> If RCU priority boosting is to be meaningful, callback invocation must
> be boosted in addition to preempted RCU readers. Otherwise, in presence
> of CPU real-time threads, the grace period ends, but the callbacks don't
> get invoked. If the callbacks don't get invoked, the associated memory
> doesn't get freed, so the system is still subject to OOM.
>
> But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
> moves the callback invocations to a kthread, which can be boosted easily.
>
> Also add comments and properly synchronized all accesses to
> rcu_cpu_kthread_task, as suggested by Lai Jiangshan.
>
> Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> ---
[snip]
> + * Drop to non-real-time priority and yield, but only after posting a
> + * timer that will cause us to regain our real-time priority if we
> + * remain preempted. Either way, we restore our real-time priority
> + * before returning.
> + */
> +static void rcu_yield(int cpu)
> +{
> + struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu);
> + struct sched_param sp;
> + struct timer_list yield_timer;
> +
> + setup_timer(&yield_timer, rcu_cpu_kthread_timer, (unsigned long)rdp);
setup_timer_on_stack() should be used here :)
Thanks,
Yong
--
Only stand for myself
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists