Messages in this thread Patch in this message |  | | From | "Paul E. McKenney" <> | | Subject | [PATCH rcu 7/9] rcu: limit PREEMPT_RCU configurations | | Date | Thu, 16 Jan 2025 12:13:25 -0800 |
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From: Ankur Arora <ankur.a.arora@oracle.com>
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 <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index 582d461c9ab7d..80242957fa417 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 -- 2.40.1
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