From: Ankur Arora Date: Fri, 13 Dec 2024 04:06:58 +0000 (-0800) Subject: rcu: limit PREEMPT_RCU configurations X-Git-Tag: v6.15-rc1~221^2^2~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8437bb84bc554fed7a716408cbb2b0e3bd13356e;p=thirdparty%2Fkernel%2Flinux.git 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 --- diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index e2206f3a070ca..dd6251678e99d 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