From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
rostedt@goodmis.org, Ankur Arora <ankur.a.arora@oracle.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH rcu v2] 7/9] rcu: limit PREEMPT_RCU configurations
Date: Thu, 30 Jan 2025 10:55:20 -0800 [thread overview]
Message-ID: <20250130185522.1652093-7-paulmck@kernel.org> (raw)
In-Reply-To: <9bc6e5fe-d49f-495a-9f55-537ed97a3615@paulmck-laptop>
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 582d461c9ab7..80242957fa41 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
next prev parent reply other threads:[~2025-01-30 18:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-16 20:13 [PATCH rcu 0/9] Lazy-preemption-related updates Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 1/9] rcu: fix header guard for rcu_all_qs() Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 2/9] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 3/9] sched: update __cond_resched comment about RCU quiescent states Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 4/9] rcu: handle unstable rdp in rcu_read_unlock_strict() Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 5/9] rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 6/9] osnoise: provide quiescent states Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 7/9] rcu: limit PREEMPT_RCU configurations Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 8/9] rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y Paul E. McKenney
2025-01-16 20:13 ` [PATCH rcu 9/9] rcutorture: Make scenario TREE07 " Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu 0/9] Lazy-preemption-related updates Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 1/9] rcu: fix header guard for rcu_all_qs() Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 2/9] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 3/9] sched: update __cond_resched comment about RCU quiescent states Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 4/9] rcu: handle unstable rdp in rcu_read_unlock_strict() Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 5/9] rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 6/9] osnoise: provide quiescent states Paul E. McKenney
2025-01-30 18:55 ` Paul E. McKenney [this message]
2025-01-30 18:55 ` [PATCH rcu v2] 8/9] rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y Paul E. McKenney
2025-01-30 18:55 ` [PATCH rcu v2] 9/9] rcutorture: Make scenario TREE07 " Paul E. McKenney
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