From 8437bb84bc554fed7a716408cbb2b0e3bd13356e Mon Sep 17 00:00:00 2001 From: Ankur Arora Date: Thu, 12 Dec 2024 20:06:58 -0800 Subject: [PATCH] rcu: limit PREEMPT_RCU configurations PREEMPT_LAZY can be enabled stand-alone or alongside PREEMPT_DYNAMIC which allows for dynamic switching of preemption models. The choice of PREEMPT_RCU or not, however, is fixed at compile time. Given that PREEMPT_RCU makes some trade-offs to optimize for latency as opposed to throughput, configurations with limited preemption might prefer the stronger forward-progress guarantees of PREEMPT_RCU=n. Accordingly, explicitly limit PREEMPT_RCU=y to the latency oriented preemption models: PREEMPT, PREEMPT_RT, and the runtime configurable model PREEMPT_DYNAMIC. This means the throughput oriented models, PREEMPT_NONE, PREEMPT_VOLUNTARY, and PREEMPT_LAZY will run with PREEMPT_RCU=n. Cc: Paul E. McKenney Cc: Peter Zijlstra Reviewed-by: Frederic Weisbecker Signed-off-by: Ankur Arora Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng --- kernel/rcu/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index e2206f3a070c..dd6251678e99 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -18,7 +18,7 @@ config TREE_RCU config PREEMPT_RCU bool - default y if PREEMPTION + default y if (PREEMPT || PREEMPT_RT || PREEMPT_DYNAMIC) select TREE_RCU help This option selects the RCU implementation that is