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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com,
	torvalds@linux-foundation.org, npiggin@gmail.com,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 13/21] rcu: Clear request other than RCU_GP_FLAG_INIT at GP end
Date: Sun, 22 Apr 2018 20:03:36 -0700	[thread overview]
Message-ID: <1524452624-27589-13-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180423030258.GA23370@linux.vnet.ibm.com>

Once the grace period has ended, any RCU_GP_FLAG_FQS requests are
irrelevant:  The grace period has ended, so there is no longer any
point in forcing quiescent states in order to try to make it end sooner.
This commit therefore causes rcu_gp_cleanup() to clear any bits other
than RCU_GP_FLAG_INIT from ->gp_flags at the end of the grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c7b1e6b2a3da..25dbbc753fef 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2181,6 +2181,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
 				       READ_ONCE(rsp->gpnum),
 				       TPS("newreq"));
 	}
+	WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
 	raw_spin_unlock_irq_rcu_node(rnp);
 }
 
-- 
2.5.2

  parent reply	other threads:[~2018-04-23  3:04 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-23  3:02 [PATCH tip/core/rcu 0/21] Contention reduction for v4.18 Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 01/21] rcu: Improve non-root rcu_cbs_completed() accuracy Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 02/21] rcu: Make rcu_start_future_gp()'s grace-period check more precise Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 03/21] rcu: Add accessor macros for the ->need_future_gp[] array Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 04/21] rcu: Make rcu_gp_kthread() check for early-boot activity Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 05/21] rcu: Make rcu_gp_cleanup() more accurately predict need for new GP Paul E. McKenney
2018-05-10  7:21   ` [tip/core/rcu, " Joel Fernandes
2018-05-10 13:15     ` Paul E. McKenney
2018-05-10 17:22       ` Joel Fernandes
2018-05-11 16:22         ` Paul E. McKenney
2018-05-10 17:37       ` Joel Fernandes
2018-05-11 16:24         ` Paul E. McKenney
2018-05-11 16:27           ` Joel Fernandes
2018-04-23  3:03 ` [PATCH tip/core/rcu 06/21] rcu: Avoid losing ->need_future_gp[] values due to GP start/end races Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 07/21] rcu: Make rcu_future_needs_gp() check all ->need_future_gps[] elements Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 08/21] rcu: Convert ->need_future_gp[] array to boolean Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 09/21] rcu: Make rcu_migrate_callbacks wake GP kthread when needed Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 10/21] rcu: Avoid __call_rcu_core() root rcu_node ->lock acquisition Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 11/21] rcu: Switch __rcu_process_callbacks() to rcu_accelerate_cbs() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 12/21] rcu: Cleanup, don't put ->completed into an int Paul E. McKenney
2018-04-23  3:03 ` Paul E. McKenney [this message]
2018-04-23  3:03 ` [PATCH tip/core/rcu 14/21] rcu: Inline rcu_start_gp_advanced() into rcu_start_future_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 15/21] rcu: Make rcu_start_future_gp() caller select grace period Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 16/21] rcu: Add funnel locking to rcu_start_this_gp() Paul E. McKenney
2018-05-12  6:03   ` [tip/core/rcu,16/21] " Joel Fernandes
2018-05-12 14:40     ` Paul E. McKenney
2018-05-12 14:44       ` Paul E. McKenney
2018-05-12 23:53         ` Joel Fernandes
2018-05-13 15:38           ` Paul E. McKenney
2018-05-13 16:49             ` Joel Fernandes
2018-05-13 19:09               ` Paul E. McKenney
2018-05-13 19:51                 ` Joel Fernandes
2018-05-14  2:22                   ` Paul E. McKenney
2018-05-14  5:00                     ` Joel Fernandes
2018-05-14 13:23                       ` Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 17/21] rcu: Make rcu_start_this_gp() check for out-of-range requests Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 18/21] rcu: The rcu_gp_cleanup() function does not need cpu_needs_another_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 19/21] rcu: Simplify and inline cpu_needs_another_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 20/21] rcu: Drop early GP request check from rcu_gp_kthread() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 21/21] rcu: Update list of rcu_future_grace_period() trace events Paul E. McKenney
2018-05-14  6:42 ` [PATCH tip/core/rcu 0/21] Contention reduction for v4.18 Nicholas Piggin
2018-05-14 16:09   ` Paul E. McKenney
2018-05-14 22:21     ` Nicholas Piggin
2018-05-14 22:42       ` Paul E. McKenney

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