From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.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>,
Martin Lau <kafai@fb.com>,
Neeraj Upadhyay <neeraj.iitr10@gmail.com>
Subject: [PATCH rcu 10/18] rcu-tasks: Abstract invocations of callbacks
Date: Wed, 1 Dec 2021 16:38:50 -0800 [thread overview]
Message-ID: <20211202003858.3129628-10-paulmck@kernel.org> (raw)
In-Reply-To: <20211202003826.GA3129369@paulmck-ThinkPad-P17-Gen-1>
This commit adds a rcu_tasks_invoke_cbs() function that invokes all
ready callbacks on all of the per-CPU lists that are currently in use.
Reported-by: Martin Lau <kafai@fb.com>
Cc: Neeraj Upadhyay <neeraj.iitr10@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tasks.h | 58 ++++++++++++++++++++++++++++------------------
1 file changed, 35 insertions(+), 23 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index bb37d4a4e48de..3bc0edb6a7bb6 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -256,14 +256,43 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
return needgpcb;
}
-/* RCU-tasks kthread that detects grace periods and invokes callbacks. */
-static int __noreturn rcu_tasks_kthread(void *arg)
+// Advance callbacks and invoke any that are ready.
+static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp)
{
+ int cpu;
unsigned long flags;
int len;
- int needgpcb;
struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
struct rcu_head *rhp;
+
+ for (cpu = 0; cpu < rtp->percpu_enqueue_lim; cpu++) {
+ struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
+
+ if (rcu_segcblist_empty(&rtpcp->cblist))
+ continue;
+ raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
+ smp_mb__after_spinlock(); // Order updates vs. GP.
+ rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
+ rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl);
+ raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
+ len = rcl.len;
+ for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) {
+ local_bh_disable();
+ rhp->func(rhp);
+ local_bh_enable();
+ cond_resched();
+ }
+ raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
+ rcu_segcblist_add_len(&rtpcp->cblist, -len);
+ (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
+ raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
+ }
+}
+
+/* RCU-tasks kthread that detects grace periods and invokes callbacks. */
+static int __noreturn rcu_tasks_kthread(void *arg)
+{
+ int needgpcb;
struct rcu_tasks *rtp = arg;
/* Run on housekeeping CPUs by default. Sysadm can move if desired. */
@@ -277,8 +306,6 @@ static int __noreturn rcu_tasks_kthread(void *arg)
* This loop is terminated by the system going down. ;-)
*/
for (;;) {
- struct rcu_tasks_percpu *rtpcp;
-
set_tasks_gp_state(rtp, RTGS_WAIT_CBS);
/* If there were none, wait a bit and start over. */
@@ -293,25 +320,10 @@ static int __noreturn rcu_tasks_kthread(void *arg)
rcu_seq_end(&rtp->tasks_gp_seq);
}
- /* Invoke the callbacks. */
+ /* Invoke callbacks. */
set_tasks_gp_state(rtp, RTGS_INVOKE_CBS);
- rtpcp = per_cpu_ptr(rtp->rtpcpu, 0);
- raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
- smp_mb__after_spinlock(); // Order updates vs. GP.
- rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
- rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl);
- raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
- len = rcl.len;
- for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) {
- local_bh_disable();
- rhp->func(rhp);
- local_bh_enable();
- cond_resched();
- }
- raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
- rcu_segcblist_add_len(&rtpcp->cblist, -len);
- (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq));
- raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
+ rcu_tasks_invoke_cbs(rtp);
+
/* Paranoid sleep to keep this from entering a tight loop */
schedule_timeout_idle(rtp->gp_sleep);
}
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2021-12-02 0:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-02 0:38 [PATCH rcu 0/18] RCU Tasks updates for v5.17 Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 01/18] rcu-tasks: Don't remove tasks with pending IPIs from holdout list Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 02/18] rcu-tasks: Create per-CPU callback lists Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 03/18] rcu-tasks: Introduce ->percpu_enqueue_shift for dynamic queue selection Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 04/18] rcu-tasks: Convert grace-period counter to grace-period sequence number Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 05/18] rcu_tasks: Convert bespoke callback list to rcu_segcblist structure Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 06/18] rcu-tasks: Use spin_lock_rcu_node() and friends Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 07/18] rcu-tasks: Inspect stalled task's trc state in locked state Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 08/18] rcu-tasks: Add a ->percpu_enqueue_lim to the rcu_tasks structure Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 09/18] rcu-tasks: Abstract checking of callback lists Paul E. McKenney
2021-12-02 0:38 ` Paul E. McKenney [this message]
2021-12-02 0:38 ` [PATCH rcu 11/18] rcu-tasks: Use workqueues for multiple rcu_tasks_invoke_cbs() invocations Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 12/18] rcu-tasks: Make rcu_barrier_tasks*() handle multiple callback queues Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 13/18] rcu-tasks: Add rcupdate.rcu_task_enqueue_lim to set initial queueing Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 14/18] rcu-tasks: Count trylocks to estimate call_rcu_tasks() contention Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 15/18] rcu-tasks: Avoid raw-spinlocked wakeups from call_rcu_tasks_generic() Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 16/18] rcu-tasks: Use more callback queues if contention encountered Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 17/18] rcu-tasks: Use separate ->percpu_dequeue_lim for callback dequeueing Paul E. McKenney
2021-12-02 0:38 ` [PATCH rcu 18/18] rcu-tasks: Use fewer callbacks queues if callback flood ends Paul E. McKenney
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