From 9fc98e3143de7b7e8d766aef41b46ec0bc0ae4ca Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 4 Mar 2021 14:46:59 -0800 Subject: [PATCH] rcu-tasks: Add block comment laying out RCU Rude design 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 --- 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) -- 2.11.0