From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH RFC tip/core/rcu 2/5] rcu: Short-circuit normal GPs via expedited GPs
Date: Wed, 1 Jul 2015 06:41:44 -0700 [thread overview]
Message-ID: <20150701134143.GY3717@linux.vnet.ibm.com> (raw)
In-Reply-To: <20150701100521.GP19282@twins.programming.kicks-ass.net>
On Wed, Jul 01, 2015 at 12:05:21PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 30, 2015 at 02:48:27PM -0700, Paul E. McKenney wrote:
> > rsp->gp_state = RCU_GP_WAIT_FQS;
> > ret = wait_event_interruptible_timeout(rsp->gp_wq,
> > + ((gf = READ_ONCE(rsp->gp_flags)) &
> > + RCU_GP_FLAG_FQS) ||
> > + (!READ_ONCE(rnp->qsmask) &&
> > + !rcu_preempt_blocked_readers_cgp(rnp)) ||
> > + rcu_exp_gp_seq_done(rsp->exp_rsp,
> > + rsp->gp_exp_snap),
> > + j);
> > rsp->gp_state = RCU_GP_DONE_FQS;
>
> How can the GP be done if we timed out or got interrupted?
If all the CPUs still blocking the grace period went idle, or in a
NO_HZ_FULL kernel, entered nohz_full userspace execution. Or, if
certain low-probability races happen, went offline.
Thanx, Paul
next prev parent reply other threads:[~2015-07-01 13:42 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-30 21:48 [PATCH RFC tip/core/rcu 0/5] Expedited grace periods encouraging normal ones Paul E. McKenney
2015-06-30 21:48 ` [PATCH RFC tip/core/rcu 1/5] rcu: Prepare for expedited GP driving normal GP Paul E. McKenney
2015-06-30 21:48 ` [PATCH RFC tip/core/rcu 2/5] rcu: Short-circuit normal GPs via expedited GPs Paul E. McKenney
2015-07-01 10:03 ` Peter Zijlstra
2015-07-01 13:42 ` Paul E. McKenney
2015-07-01 20:59 ` Paul E. McKenney
2015-07-01 10:05 ` Peter Zijlstra
2015-07-01 13:41 ` Paul E. McKenney [this message]
2015-07-01 13:48 ` Peter Zijlstra
2015-07-01 14:03 ` Paul E. McKenney
2015-07-02 12:03 ` Peter Zijlstra
2015-07-02 14:06 ` Paul E. McKenney
2015-07-02 16:48 ` Peter Zijlstra
2015-07-02 19:35 ` Paul E. McKenney
2015-07-06 14:52 ` Peter Zijlstra
2015-06-30 21:48 ` [PATCH RFC tip/core/rcu 3/5] rcutorture: Ensure that normal GPs advance without " Paul E. McKenney
2015-06-30 21:48 ` [PATCH RFC tip/core/rcu 4/5] rcu: Wake grace-period kthread at end of expedited grace period Paul E. McKenney
2015-06-30 21:48 ` [PATCH RFC tip/core/rcu 5/5] rcu: Limit expedited helping to every 10 ms or every 4th GP Paul E. McKenney
2015-06-30 21:56 ` Eric Dumazet
2015-06-30 22:10 ` Paul E. McKenney
2015-07-01 10:07 ` Peter Zijlstra
2015-07-01 13:45 ` Paul E. McKenney
2015-07-01 19:30 ` Paul E. McKenney
2015-06-30 22:00 ` [PATCH RFC tip/core/rcu 0/5] Expedited grace periods encouraging normal ones josh
2015-06-30 22:12 ` Paul E. McKenney
2015-06-30 23:46 ` josh
2015-07-01 0:15 ` Paul E. McKenney
2015-07-01 0:42 ` Josh Triplett
2015-07-01 3:37 ` Paul E. McKenney
2015-07-01 10:12 ` Peter Zijlstra
2015-07-01 14:01 ` Paul E. McKenney
2015-07-01 14:08 ` Eric Dumazet
2015-07-01 15:58 ` Paul E. McKenney
2015-07-01 15:43 ` Josh Triplett
2015-07-01 15:59 ` Paul E. McKenney
2015-07-01 10:09 ` Peter Zijlstra
2015-07-01 10:55 ` Peter Zijlstra
2015-07-01 14:00 ` Paul E. McKenney
2015-07-01 14:17 ` Peter Zijlstra
2015-07-01 16:17 ` Paul E. McKenney
2015-07-01 17:02 ` Peter Zijlstra
2015-07-01 20:09 ` Paul E. McKenney
2015-07-01 21:20 ` josh
2015-07-01 21:49 ` Paul E. McKenney
2015-07-02 7:47 ` Ingo Molnar
2015-07-02 13:58 ` Paul E. McKenney
2015-07-02 18:35 ` Ingo Molnar
2015-07-02 18:47 ` Mathieu Desnoyers
2015-07-02 19:23 ` Paul E. McKenney
2015-07-02 21:07 ` Mathieu Desnoyers
2015-07-02 19:22 ` Paul E. McKenney
2015-07-02 1:11 ` Mike Galbraith
2015-07-02 1:34 ` josh
2015-07-02 1:59 ` Mike Galbraith
2015-07-02 2:18 ` Paul E. McKenney
2015-07-02 2:50 ` Mike Galbraith
2015-07-02 3:15 ` Paul E. McKenney
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