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>
Subject: [PATCH tip/core/rcu 2/4] rcu-tasks: Add block comment laying out RCU Rude design
Date: Tue, 11 May 2021 16:09:40 -0700 [thread overview]
Message-ID: <20210511230942.2894861-2-paulmck@kernel.org> (raw)
In-Reply-To: <20210511230720.GA2894512@paulmck-ThinkPad-P17-Gen-1>
This commit adds a block comment that gives a high-level overview of
how RCU Rude grace periods progress. It also gives an overview of the
memory ordering.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/tasks.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 94d2c2c7f0ab..d6aa352cd705 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -645,8 +645,13 @@ void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
// passing an empty function to schedule_on_each_cpu(). This approach
// provides an asynchronous call_rcu_tasks_rude() API and batching
// of concurrent calls to the synchronous synchronize_rcu_rude() API.
-// This sends IPIs far and wide and induces otherwise unnecessary context
-// switches on all online CPUs, whether idle or not.
+// This invokes schedule_on_each_cpu() in order to send IPIs far and wide
+// and induces otherwise unnecessary context switches on all online CPUs,
+// whether idle or not.
+//
+// Callback handling is provided by the rcu_tasks_kthread() function.
+//
+// Ordering is provided by the scheduler's context-switch code.
// Empty function to allow workqueues to force a context switch.
static void rcu_tasks_be_rude(struct work_struct *work)
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2021-05-11 23:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 23:07 [PATCH tip/core/rcu 0/6] SRCU updates for v5.14 Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 1/6] srcu: Remove superfluous sdp->srcu_lock_count zero filling Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 2/6] srcu: Remove superfluous ssp initialization for early callbacks Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 3/6] srcu: Unconditionally embed struct lockdep_map Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 4/6] srcu: Initialize SRCU after timers Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 5/6] srcu: Fix broken node geometry after early ssp init Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 6/6] srcu: Early test SRCU polling start Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 1/4] rcu-tasks: Add block comment laying out RCU Tasks design Paul E. McKenney
2021-05-11 23:09 ` Paul E. McKenney [this message]
2021-05-11 23:09 ` [PATCH tip/core/rcu 3/4] rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 4/4] tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline Paul E. McKenney
-- strict thread matches above, loose matches on Subject: below --
2021-05-12 18:27 [PATCH tip/core/rcu 2/4] rcu-tasks: Add block comment laying out RCU Rude design Paul E. McKenney
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