* [PATCH tip/core/rcu 2/4] rcu-tasks: Add block comment laying out RCU Rude design
@ 2021-05-12 18:27 Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2021-05-12 18:27 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, mingo, jiangshanlai, akpm,
mathieu.desnoyers, josh, tglx, peterz, rostedt, dhowells,
edumazet, fweisbec, oleg, joel, Paul E. McKenney
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH tip/core/rcu 2/4] rcu-tasks: Add block comment laying out RCU Rude design
2021-05-11 23:07 [PATCH tip/core/rcu 0/6] SRCU updates for v5.14 Paul E. McKenney
@ 2021-05-11 23:09 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2021-05-11 23:09 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, mingo, jiangshanlai, akpm,
mathieu.desnoyers, josh, tglx, peterz, rostedt, dhowells,
edumazet, fweisbec, oleg, joel, Paul E. McKenney
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
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-05-11 23:07 [PATCH tip/core/rcu 0/6] SRCU updates for v5.14 Paul E. McKenney
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