From: Peter Zijlstra <peterz@infradead.org>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: paulmck@linux.vnet.ibm.com, Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org,
Dipankar Sarma <dipankar@in.ibm.com>
Subject: Re: [PATCH 5/8] rcu: eliminate deadlock for rcu read site
Date: Mon, 12 Aug 2013 15:55:44 +0200 [thread overview]
Message-ID: <20130812135544.GG27162@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5204B6EF.6000905@cn.fujitsu.com>
On Fri, Aug 09, 2013 at 05:31:27PM +0800, Lai Jiangshan wrote:
> On 08/09/2013 04:40 AM, Paul E. McKenney wrote:
> > One problem here -- it may take quite some time for a set_need_resched()
> > to take effect. This is especially a problem for RCU priority boosting,
> > but can also needlessly delay preemptible-RCU grace periods because
> > local_irq_restore() and friends don't check the TIF_NEED_RESCHED bit.
>
>
> The final effect of deboosting(rt_mutex_unlock()) is also accomplished
> via set_need_resched()/set_tsk_need_resched().
> set_need_resched() is enough for RCU priority boosting issue here.
But there's a huge difference between the boosting and deboosting side
of things. rcu_read_unlock_special() starts the boost, the deboosting
only matters if/when you reschedule.
next prev parent reply other threads:[~2013-08-12 13:55 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-07 10:24 [PATCH 0/8] rcu: Ensure rcu read site is deadlock-immunity Lai Jiangshan
2013-08-07 10:24 ` [PATCH 1/8] rcu: add a warn to rcu_preempt_note_context_switch() Lai Jiangshan
2013-10-30 11:02 ` Paul E. McKenney
2013-08-07 10:24 ` [PATCH 2/8] rcu: remove irq/softirq context check in rcu_read_unlock_special() Lai Jiangshan
2013-10-30 11:18 ` Paul E. McKenney
2013-08-07 10:24 ` [PATCH 3/8] rcu: keep irqs disabled " Lai Jiangshan
2013-08-07 10:25 ` [PATCH 4/8] rcu: delay task rcu state cleanup in exit_rcu() Lai Jiangshan
2013-08-07 10:25 ` [PATCH 5/8] rcu: eliminate deadlock for rcu read site Lai Jiangshan
2013-08-08 20:40 ` Paul E. McKenney
2013-08-09 9:31 ` Lai Jiangshan
2013-08-09 17:58 ` Paul E. McKenney
2013-08-12 13:55 ` Peter Zijlstra [this message]
2013-08-12 15:16 ` Paul E. McKenney
2013-08-12 16:21 ` Peter Zijlstra
2013-08-12 16:44 ` Paul E. McKenney
2013-08-10 3:43 ` Lai Jiangshan
2013-08-10 15:07 ` Paul E. McKenney
2013-08-10 15:08 ` Paul E. McKenney
2013-08-21 3:17 ` Paul E. McKenney
2013-08-21 3:25 ` Lai Jiangshan
2013-08-21 13:42 ` Paul E. McKenney
2013-08-12 13:53 ` Peter Zijlstra
2013-08-12 14:10 ` Steven Rostedt
2013-08-12 14:14 ` Peter Zijlstra
[not found] ` <CACvQF51-oAGkdxwku+orKSQ=SZd1A4saXzkrgcRGi+KnZUZYxQ@mail.gmail.com>
2013-08-22 14:34 ` Steven Rostedt
2013-08-22 14:41 ` Steven Rostedt
2013-08-23 6:26 ` Lai Jiangshan
[not found] ` <CACvQF51kcLrJsa=zBKhLkJfFBh109TW+Zrepm+tRxmEp0gALbQ@mail.gmail.com>
2013-08-25 17:43 ` Paul E. McKenney
2013-08-26 2:39 ` Lai Jiangshan
2013-08-30 2:05 ` Paul E. McKenney
2013-09-05 15:22 ` Steven Rostedt
2013-08-07 10:25 ` [PATCH 6/8] rcu: call rcu_read_unlock_special() in rcu_preempt_check_callbacks() Lai Jiangshan
2013-08-07 10:25 ` [PATCH 7/8] rcu: add # of deferred _special() statistics Lai Jiangshan
2013-08-07 16:42 ` Paul E. McKenney
2013-08-07 10:25 ` [PATCH 8/8] rcu: remove irq work for rsp_wakeup() Lai Jiangshan
2013-08-07 12:38 ` [PATCH 0/8] rcu: Ensure rcu read site is deadlock-immunity Paul E. McKenney
2013-08-07 19:29 ` Carsten Emde
2013-08-07 19:52 ` Paul E. McKenney
2013-08-08 1:17 ` Lai Jiangshan
2013-08-08 0:36 ` Paul E. McKenney
2013-08-08 1:47 ` Lai Jiangshan
2013-08-08 2:12 ` Steven Rostedt
2013-08-08 2:33 ` Lai Jiangshan
2013-08-08 2:33 ` Paul E. McKenney
2013-08-08 3:10 ` Lai Jiangshan
2013-08-08 4:18 ` Paul E. McKenney
2013-08-08 5:27 ` Lai Jiangshan
2013-08-08 7:05 ` Paul E. McKenney
2013-08-08 2:45 ` Lai Jiangshan
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