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Tue, 13 Feb 2024 05:56:11 +0000 Received: from CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::91b3:fd53:a6ee:8685]) by CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::91b3:fd53:a6ee:8685%4]) with mapi id 15.20.7270.036; Tue, 13 Feb 2024 05:56:11 +0000 From: Ankur Arora To: linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, peterz@infradead.org, torvalds@linux-foundation.org, paulmck@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de, jpoimboe@kernel.org, mark.rutland@arm.com, jgross@suse.com, andrew.cooper3@citrix.com, bristot@kernel.org, mathieu.desnoyers@efficios.com, geert@linux-m68k.org, glaubitz@physik.fu-berlin.de, anton.ivanov@cambridgegreys.com, mattst88@gmail.com, krypton@ulrich-teichert.org, rostedt@goodmis.org, David.Laight@ACULAB.COM, richard@nod.at, mjguzik@gmail.com, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, Ankur Arora Subject: [PATCH 12/30] rcu: limit PREEMPT_RCU to full preemption under PREEMPT_AUTO Date: Mon, 12 Feb 2024 21:55:36 -0800 Message-Id: <20240213055554.1802415-13-ankur.a.arora@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20240213055554.1802415-1-ankur.a.arora@oracle.com> References: <20240213055554.1802415-1-ankur.a.arora@oracle.com> X-ClientProxiedBy: MW4PR04CA0059.namprd04.prod.outlook.com (2603:10b6:303:6a::34) To CO6PR10MB5409.namprd10.prod.outlook.com (2603:10b6:5:357::14) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO6PR10MB5409:EE_|CY8PR10MB6906:EE_ X-MS-Office365-Filtering-Correlation-Id: d8f6811a-4a49-4a32-f4c1-08dc2c587ad5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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The RCU model, however, is fixed at compile time. Now, RCU typically selects PREEMPT_RCU if CONFIG_PREEMPTION is enabled. Given the trade-offs between PREEMPT_RCU=y and PREEMPT_RCU=n, some configurations might prefer the stronger forward-progress guarantees of PREEMPT_RCU=n. Accordingly, select PREEMPT_RCU=y only if the user selects CONFIG_PREEMPT at compile time. Suggested-by: Paul E. McKenney Signed-off-by: Ankur Arora --- kernel/rcu/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index bdd7eadb33d8..d0ecc8ef17a7 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_DYNAMIC || PREEMPT_RT) select TREE_RCU help This option selects the RCU implementation that is