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From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
	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@joelfernandes.org,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH v4 tip/core/rcu 27/38] rcu-tasks: Avoid IPIing userspace/idle tasks if kernel is so built
Date: Wed, 15 Apr 2020 11:19:30 -0700
Message-ID: <20200415181941.11653-27-paulmck@kernel.org> (raw)
In-Reply-To: <20200415181856.GA11037@paulmck-ThinkPad-P72>

From: "Paul E. McKenney" <paulmck@kernel.org>

Systems running CPU-bound real-time task do not want IPIs sent to CPUs
executing nohz_full userspace tasks.  Battery-powered systems don't
want IPIs sent to idle CPUs in low-power mode.  Unfortunately, RCU tasks
trace can and will send such IPIs in some cases.

Both of these situations occur only when the target CPU is in RCU
dyntick-idle mode, in other words, when RCU is not watching the
target CPU.  This suggests that CPUs in dyntick-idle mode should use
memory barriers in outermost invocations of rcu_read_lock_trace()
and rcu_read_unlock_trace(), which would allow the RCU tasks trace
grace period to directly read out the target CPU's read-side state.
One challenge is that RCU tasks trace is not targeting a specific
CPU, but rather a task.  And that task could switch from one CPU to
another at any time.

This commit therefore uses try_invoke_on_locked_down_task()
and checks for task_curr() in trc_inspect_reader_notrunning().
When this condition holds, the target task is running and cannot move.
If CONFIG_TASKS_TRACE_RCU_READ_MB=y, the new rcu_dynticks_zero_in_eqs()
function can be used to check if the specified integer (in this case,
t->trc_reader_nesting) is zero while the target CPU remains in that same
dyntick-idle sojourn.  If so, the target task is in a quiescent state.
If not, trc_read_check_handler() must indicate failure so that the
grace-period kthread can take appropriate action or retry after an
appropriate delay, as the case may be.

With this change, given CONFIG_TASKS_TRACE_RCU_READ_MB=y, if a given
CPU remains idle or a given task continues executing in nohz_full mode,
the RCU tasks trace grace-period kthread will detect this without the
need to send an IPI.

Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/rcu.h         |  2 ++
 kernel/rcu/tasks.h       | 36 ++++++++++++++++++++++++++----------
 kernel/rcu/tree.c        | 24 ++++++++++++++++++++++++
 kernel/rcu/tree.h        |  2 ++
 kernel/rcu/tree_plugin.h | 18 ++++++++++++++++++
 5 files changed, 72 insertions(+), 10 deletions(-)

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index e1089fd..296f926 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -501,6 +501,7 @@ void srcutorture_get_gp_data(enum rcutorture_type test_type,
 #endif
 
 #ifdef CONFIG_TINY_RCU
+static inline bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) { return false; }
 static inline unsigned long rcu_get_gp_seq(void) { return 0; }
 static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
 static inline unsigned long
@@ -510,6 +511,7 @@ static inline void show_rcu_gp_kthreads(void) { }
 static inline int rcu_get_gp_kthreads_prio(void) { return 0; }
 static inline void rcu_fwd_progress_check(unsigned long j) { }
 #else /* #ifdef CONFIG_TINY_RCU */
+bool rcu_dynticks_zero_in_eqs(int cpu, int *vp);
 unsigned long rcu_get_gp_seq(void);
 unsigned long rcu_exp_batches_completed(void);
 unsigned long srcu_batches_completed(struct srcu_struct *sp);
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 64a5b97..3eed886 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -806,22 +806,38 @@ static void trc_read_check_handler(void *t_in)
 /* Callback function for scheduler to check locked-down task.  */
 static bool trc_inspect_reader(struct task_struct *t, void *arg)
 {
-	if (task_curr(t))
-		return false;  // It is running, so decline to inspect it.
+	int cpu = task_cpu(t);
+	bool in_qs = false;
+
+	if (task_curr(t)) {
+		// If no chance of heavyweight readers, do it the hard way.
+		if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
+			return false;
+
+		// If heavyweight readers are enabled on the remote task,
+		// we can inspect its state despite its currently running.
+		// However, we cannot safely change its state.
+		if (!rcu_dynticks_zero_in_eqs(cpu, &t->trc_reader_nesting))
+			return false; // No quiescent state, do it the hard way.
+		in_qs = true;
+	} else {
+		in_qs = likely(!t->trc_reader_nesting);
+	}
 
 	// Mark as checked.  Because this is called from the grace-period
 	// kthread, also remove the task from the holdout list.
 	t->trc_reader_checked = true;
 	trc_del_holdout(t);
 
-	// If the task is in a read-side critical section, set up its
-	// its state so that it will awaken the grace-period kthread upon
-	// exit from that critical section.
-	if (unlikely(t->trc_reader_nesting)) {
-		atomic_inc(&trc_n_readers_need_end); // One more to wait on.
-		WARN_ON_ONCE(t->trc_reader_special.b.need_qs);
-		WRITE_ONCE(t->trc_reader_special.b.need_qs, true);
-	}
+	if (in_qs)
+		return true;  // Already in quiescent state, done!!!
+
+	// The task is in a read-side critical section, so set up its
+	// state so that it will awaken the grace-period kthread upon exit
+	// from that critical section.
+	atomic_inc(&trc_n_readers_need_end); // One more to wait on.
+	WARN_ON_ONCE(t->trc_reader_special.b.need_qs);
+	WRITE_ONCE(t->trc_reader_special.b.need_qs, true);
 	return true;
 }
 
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e54a8a1..7dd7a17 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -252,6 +252,7 @@ static void rcu_dynticks_eqs_enter(void)
 	 * critical sections, and we also must force ordering with the
 	 * next idle sojourn.
 	 */
+	rcu_dynticks_task_trace_enter();  // Before ->dynticks update!
 	seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
 	// RCU is no longer watching.  Better be in extended quiescent state!
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
@@ -278,6 +279,7 @@ static void rcu_dynticks_eqs_exit(void)
 	 */
 	seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
 	// RCU is now watching.  Better not be in an extended quiescent state!
+	rcu_dynticks_task_trace_exit();  // After ->dynticks update!
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 		     !(seq & RCU_DYNTICK_CTRL_CTR));
 	if (seq & RCU_DYNTICK_CTRL_MASK) {
@@ -350,6 +352,28 @@ static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
 }
 
 /*
+ * Return true if the referenced integer is zero while the specified
+ * CPU remains within a single extended quiescent state.
+ */
+bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
+{
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
+	int snap;
+
+	// If not quiescent, force back to earlier extended quiescent state.
+	snap = atomic_read(&rdp->dynticks) & ~(RCU_DYNTICK_CTRL_MASK |
+					       RCU_DYNTICK_CTRL_CTR);
+
+	smp_rmb(); // Order ->dynticks and *vp reads.
+	if (READ_ONCE(*vp))
+		return false;  // Non-zero, so report failure;
+	smp_rmb(); // Order *vp read and ->dynticks re-read.
+
+	// If still in the same extended quiescent state, we are good!
+	return snap == (atomic_read(&rdp->dynticks) & ~RCU_DYNTICK_CTRL_MASK);
+}
+
+/*
  * Set the special (bottom) bit of the specified CPU so that it
  * will take special action (such as flushing its TLB) on the
  * next exit from an extended quiescent state.  Returns true if
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 9dc2ec0..29ba799 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -454,6 +454,8 @@ static void rcu_bind_gp_kthread(void);
 static bool rcu_nohz_full_cpu(void);
 static void rcu_dynticks_task_enter(void);
 static void rcu_dynticks_task_exit(void);
+static void rcu_dynticks_task_trace_enter(void);
+static void rcu_dynticks_task_trace_exit(void);
 
 /* Forward declarations for tree_stall.h */
 static void record_gp_stall_check_time(void);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 37e0281..4cef7e3 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2552,3 +2552,21 @@ static void rcu_dynticks_task_exit(void)
 	WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
 #endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
 }
+
+/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */
+static void rcu_dynticks_task_trace_enter(void)
+{
+#ifdef CONFIG_TASKS_RCU_TRACE
+	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
+		current->trc_reader_special.b.need_mb = true;
+#endif /* #ifdef CONFIG_TASKS_RCU_TRACE */
+}
+
+/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */
+static void rcu_dynticks_task_trace_exit(void)
+{
+#ifdef CONFIG_TASKS_RCU_TRACE
+	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
+		current->trc_reader_special.b.need_mb = false;
+#endif /* #ifdef CONFIG_TASKS_RCU_TRACE */
+}
-- 
2.9.5


  parent reply index

Thread overview: 171+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12 18:16 [PATCH RFC tip/core/rcu 0/16] Prototype RCU usable from idle, exception, offline Paul E. McKenney
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 01/16] sched/core: Add function to sample state of non-running function paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 02/16] rcu: Add per-task state to RCU CPU stall warnings paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 03/16] rcutorture: Add flag to produce non-busy-wait task stalls paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 04/16] rcu-tasks: Move Tasks RCU to its own file paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 05/16] rcu-tasks: Create struct to hold state information paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 06/16] rcu: Reinstate synchronize_rcu_mult() paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 07/16] rcutorture: Add a test for synchronize_rcu_mult() paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 08/16] rcu-tasks: Refactor RCU-tasks to allow variants to be added paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 09/16] rcu-tasks: Add an RCU-tasks rude variant paulmck
2020-03-16 19:47   ` Joel Fernandes
2020-03-16 20:17     ` Joel Fernandes
2020-03-16 20:32       ` Paul E. McKenney
2020-03-16 21:32         ` Steven Rostedt
2020-03-16 21:45           ` Joel Fernandes
2020-03-16 22:03             ` Steven Rostedt
2020-03-16 22:11               ` Paul E. McKenney
2020-05-10  9:59               ` Lai Jiangshan
2020-05-10 15:49                 ` Paul E. McKenney
2020-05-11  0:06                   ` Lai Jiangshan
2020-05-11  2:44                     ` Paul E. McKenney
2020-05-11  0:44                 ` Masami Hiramatsu
2020-05-11 16:07                 ` Steven Rostedt
2020-05-11 19:48                 ` Steven Rostedt
2020-03-16 20:29     ` Paul E. McKenney
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 10/16] rcutorture: Add torture tests for RCU Tasks Rude paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 11/16] rcu-tasks: Use unique names for RCU-Tasks kthreads and messages paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 12/16] rcu-tasks: Further refactor RCU-tasks to allow adding more variants paulmck
2020-03-12 18:16 ` [PATCH RFC tip/core/rcu 13/16] rcu-tasks: Code movement to allow more Tasks RCU variants paulmck
2020-03-12 18:17 ` [PATCH RFC tip/core/rcu 14/16] rcu: Add an RCU Tasks Trace to simplify protection of tracing hooks paulmck
2020-03-12 18:17 ` [PATCH RFC tip/core/rcu 15/16] rcutorture: Add torture tests for RCU Tasks Trace paulmck
2020-03-12 18:17 ` [PATCH RFC tip/core/rcu 16/16] rcu-tasks: Add stall warnings " paulmck
2020-03-13 14:41 ` [PATCH RFC tip/core/rcu 0/16] Prototype RCU usable from idle, exception, offline Frederic Weisbecker
2020-03-13 15:42   ` Paul E. McKenney
2020-03-15 17:45     ` Mathieu Desnoyers
2020-03-15 17:59       ` Paul E. McKenney
2020-03-16 18:36         ` Steven Rostedt
2020-03-16 18:52           ` Paul E. McKenney
2020-03-16 14:45     ` Frederic Weisbecker
2020-03-16 15:39       ` Paul E. McKenney
2020-03-19  0:10 ` [PATCH RFC v2 tip/core/rcu 0/22] " Paul E. McKenney
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 01/22] sched/core: Add function to sample state of locked-down task paulmck
2020-03-19 17:22     ` Steven Rostedt
2020-03-19 17:35       ` Paul E. McKenney
2020-03-20  2:49         ` Paul E. McKenney
2020-03-20  3:09           ` Steven Rostedt
2020-03-20 16:27             ` Paul E. McKenney
2020-03-24  0:06           ` Joel Fernandes
2020-03-24  0:15             ` Joel Fernandes
2020-03-24 16:26               ` Paul E. McKenney
2020-03-24 15:48             ` Paul E. McKenney
2020-03-24 16:52               ` Joel Fernandes
2020-03-24 17:20                 ` Paul E. McKenney
2020-03-24 18:19                   ` Joel Fernandes
2020-03-25  0:58                     ` Paul E. McKenney
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 02/22] rcu: Add per-task state to RCU CPU stall warnings paulmck
2020-03-19 17:27     ` Steven Rostedt
2020-03-19 17:41       ` Paul E. McKenney
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 03/22] rcutorture: Add flag to produce non-busy-wait task stalls paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 04/22] rcu-tasks: Move Tasks RCU to its own file paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 05/22] rcu-tasks: Create struct to hold state information paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 06/22] rcu: Reinstate synchronize_rcu_mult() paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 07/22] rcutorture: Add a test for synchronize_rcu_mult() paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 08/22] rcu-tasks: Refactor RCU-tasks to allow variants to be added paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 09/22] rcu-tasks: Add an RCU-tasks rude variant paulmck
2020-03-19 19:04     ` Steven Rostedt
2020-03-19 23:58       ` Paul E. McKenney
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 10/22] rcutorture: Add torture tests for RCU Tasks Rude paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 11/22] rcu-tasks: Use unique names for RCU-Tasks kthreads and messages paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 12/22] rcu-tasks: Further refactor RCU-tasks to allow adding more variants paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 13/22] rcu-tasks: Code movement to allow more Tasks RCU variants paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 14/22] rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks paulmck
2020-03-19  1:37     ` Joel Fernandes
2020-03-19  1:58       ` Joel Fernandes
2020-03-19  3:40         ` Paul E. McKenney
2020-03-19 19:42     ` Steven Rostedt
2020-03-20  0:28       ` Paul E. McKenney
2020-03-20  0:48         ` Steven Rostedt
2020-03-20  2:41           ` Paul E. McKenney
2020-03-28 14:06             ` Joel Fernandes
2020-03-28 15:34               ` Paul E. McKenney
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 15/22] rcutorture: Add torture tests for RCU Tasks Trace paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 16/22] rcu-tasks: Add stall warnings " paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 17/22] rcu-tasks: Move #ifdef into tasks.h paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 18/22] rcu-tasks: Add RCU tasks to rcutorture writer stall output paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 19/22] rcu-tasks: Make rcutorture writer stall output include GP state paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 20/22] rcu-tasks: Make RCU Tasks Trace make use of RCU scheduler hooks paulmck
2020-03-19  0:10   ` [PATCH RFC v2 tip/core/rcu 21/22] rcu-tasks: Add a grace-period start time for throttling and debug paulmck
2020-03-19  0:11   ` [PATCH RFC v2 tip/core/rcu 22/22] rcu-tasks: Provide boot parameter to delay IPIs until late in grace period paulmck
2020-03-19 11:31   ` [PATCH RFC v2 tip/core/rcu 0/22] Prototype RCU usable from idle, exception, offline Mathieu Desnoyers
2020-03-19 13:13     ` Paul E. McKenney
     [not found]   ` <20200319104614.11444-1-hdanton@sina.com>
2020-03-19 12:38     ` [PATCH RFC v2 tip/core/rcu 03/22] rcutorture: Add flag to produce non-busy-wait task stalls Paul E. McKenney
     [not found]     ` <20200319133947.12172-1-hdanton@sina.com>
2020-03-19 15:22       ` Paul E. McKenney
     [not found]       ` <20200320040329.9840-1-hdanton@sina.com>
2020-03-20 16:11         ` Paul E. McKenney
     [not found]   ` <20200320071228.9740-1-hdanton@sina.com>
2020-03-20 19:14     ` [PATCH RFC v2 tip/core/rcu 04/22] rcu-tasks: Move Tasks RCU to its own file Paul E. McKenney
2020-03-27 22:23   ` [PATCH RFC v3 tip/core/rcu 0/34] Prototype RCU usable from idle, exception, offline Paul E. McKenney
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 01/34] sched/core: Add function to sample state of locked-down task paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 02/34] rcu: Add per-task state to RCU CPU stall warnings paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 03/34] rcutorture: Add flag to produce non-busy-wait task stalls paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 04/34] rcu-tasks: Move Tasks RCU to its own file paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 05/34] rcu-tasks: Create struct to hold state information paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 06/34] rcu: Reinstate synchronize_rcu_mult() paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 07/34] rcutorture: Add a test for synchronize_rcu_mult() paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 08/34] rcu-tasks: Refactor RCU-tasks to allow variants to be added paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 09/34] rcu-tasks: Add an RCU-tasks rude variant paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 10/34] rcutorture: Add torture tests for RCU Tasks Rude paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 11/34] rcu-tasks: Use unique names for RCU-Tasks kthreads and messages paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 12/34] rcu-tasks: Further refactor RCU-tasks to allow adding more variants paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 13/34] rcu-tasks: Code movement to allow more Tasks RCU variants paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 14/34] rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 15/34] rcutorture: Add torture tests for RCU Tasks Trace paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 16/34] rcu-tasks: Add stall warnings " paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 17/34] rcu-tasks: Move #ifdef into tasks.h paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 18/34] rcu-tasks: Add RCU tasks to rcutorture writer stall output paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 19/34] rcu-tasks: Make rcutorture writer stall output include GP state paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 20/34] rcu-tasks: Make RCU Tasks Trace make use of RCU scheduler hooks paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 21/34] rcu-tasks: Add a grace-period start time for throttling and debug paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 22/34] rcu-tasks: Provide boot parameter to delay IPIs until late in grace period paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 23/34] rcu-tasks: Split ->trc_reader_need_end paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 24/34] rcu-tasks: Add grace-period and IPI counts to statistics paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 25/34] rcu-tasks: Add Kconfig option to mediate smp_mb() vs. IPI paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 26/34] rcu-tasks: Avoid IPIing userspace/idle tasks if kernel is so built paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 27/34] rcu-tasks: Allow rcu_read_unlock_trace() under scheduler locks paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 28/34] rcu-tasks: Disable CPU hotplug across RCU tasks trace scans paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 29/34] rcu-tasks: Handle the running-offline idle-task special case paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 30/34] rcu-tasks: Make RCU tasks trace also wait for idle tasks paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 31/34] rcu-tasks: Add rcu_dynticks_zero_in_eqs() effectiveness statistics paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 32/34] rcu-tasks: Add count for idle tasks on offline CPUs paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 33/34] rcutorture: Add TRACE02 scenario enabling RCU Tasks Trace IPIs paulmck
2020-03-27 22:24     ` [PATCH v3 tip/core/rcu 34/34] rcu-tasks: Add IPI failure count to statistics paulmck
2020-04-15 18:18     ` [PATCH v4 tip/core/rcu 0/38] Prototype RCU usable from idle, exception, offline Paul E. McKenney
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 01/38] rcu: Add comments marking transitions between RCU watching and not paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 02/38] rcu-tasks: Use context-switch hook for PREEMPT=y kernels paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 03/38] sched/core: Add function to sample state of locked-down task paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 04/38] rcu: Add per-task state to RCU CPU stall warnings paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 05/38] rcu-tasks: Move Tasks RCU to its own file paulmck
2020-05-10  7:42         ` Lai Jiangshan
2020-05-10 15:39           ` Paul E. McKenney
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 06/38] rcu-tasks: Create struct to hold state information paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 07/38] rcu: Reinstate synchronize_rcu_mult() paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 08/38] rcutorture: Add a test for synchronize_rcu_mult() paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 09/38] rcu-tasks: Refactor RCU-tasks to allow variants to be added paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 10/38] rcu-tasks: Add an RCU-tasks rude variant paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 11/38] rcutorture: Add torture tests for RCU Tasks Rude paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 12/38] rcu-tasks: Use unique names for RCU-Tasks kthreads and messages paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 13/38] rcu-tasks: Further refactor RCU-tasks to allow adding more variants paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 14/38] rcu-tasks: Code movement to allow more Tasks RCU variants paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 15/38] rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 16/38] rcutorture: Add torture tests for RCU Tasks Trace paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 17/38] rcu-tasks: Add stall warnings " paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 18/38] rcu-tasks: Move #ifdef into tasks.h paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 19/38] rcu-tasks: Add RCU tasks to rcutorture writer stall output paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 20/38] rcu-tasks: Make rcutorture writer stall output include GP state paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 21/38] rcu-tasks: Make RCU Tasks Trace make use of RCU scheduler hooks paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 22/38] rcu-tasks: Add a grace-period start time for throttling and debug paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 23/38] rcu-tasks: Provide boot parameter to delay IPIs until late in grace period paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 24/38] rcu-tasks: Split ->trc_reader_need_end paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 25/38] rcu-tasks: Add grace-period and IPI counts to statistics paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 26/38] rcu-tasks: Add Kconfig option to mediate smp_mb() vs. IPI paulmck
2020-04-15 18:19       ` paulmck [this message]
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 28/38] rcu-tasks: Allow rcu_read_unlock_trace() under scheduler locks paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 29/38] rcu-tasks: Disable CPU hotplug across RCU tasks trace scans paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 30/38] rcu-tasks: Handle the running-offline idle-task special case paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 31/38] rcu-tasks: Make RCU tasks trace also wait for idle tasks paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 32/38] rcu-tasks: Add rcu_dynticks_zero_in_eqs() effectiveness statistics paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 33/38] rcu-tasks: Add count for idle tasks on offline CPUs paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 34/38] rcutorture: Add TRACE02 scenario enabling RCU Tasks Trace IPIs paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 35/38] rcu-tasks: Add IPI failure count to statistics paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 36/38] rcu-tasks: Allow standalone use of TASKS_{TRACE_,}RCU paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 37/38] ftrace: Use synchronize_rcu_tasks_rude() instead of ftrace_sync() paulmck
2020-04-15 18:19       ` [PATCH v4 tip/core/rcu 38/38] rcu: Don't acquire lock in NMI handler in rcu_nmi_enter_common() paulmck

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