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| author | Paul E. McKenney <paulmck@kernel.org> | 2025-01-08 19:42:42 -0800 |
|---|---|---|
| committer | Boqun Feng <boqun.feng@gmail.com> | 2025-02-04 21:50:06 -0800 |
| commit | 053ca72554df6923d703a1c072f1930e1870b040 (patch) | |
| tree | b0512258b59a91cbef7d92636c1db733b0003676 | |
| parent | 366ba3f7f9ce4924d544b9d2c6514a7b19270953 (diff) | |
rcu: Add CONFIG_RCU_LAZY delays to call_rcu() kernel-doc header
This commit adds a description of the energy-efficiency delays that
call_rcu() can impose, along with a pointer to call_rcu_hurry() for
latency-sensitive kernel code.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
| -rw-r--r-- | kernel/rcu/tree.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2cd193ed854c..780e4b30febb 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3172,6 +3172,13 @@ EXPORT_SYMBOL_GPL(call_rcu_hurry); * * Implementation of these memory-ordering guarantees is described here: * Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst. + * + * Specific to call_rcu() (as opposed to the other call_rcu*() functions), + * in kernels built with CONFIG_RCU_LAZY=y, call_rcu() might delay for many + * seconds before starting the grace period needed by the corresponding + * callback. This delay can significantly improve energy-efficiency + * on low-utilization battery-powered devices. To avoid this delay, + * in latency-sensitive kernel code, use call_rcu_hurry(). */ void call_rcu(struct rcu_head *head, rcu_callback_t func) { |