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Tue, 15 Oct 2024 23:01:15 +0000 Received: from CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::25a9:32c2:a7b0:de9e]) by CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::25a9:32c2:a7b0:de9e%4]) with mapi id 15.20.8069.016; Tue, 15 Oct 2024 23:01:14 +0000 References: <20241009165411.3426937-1-ankur.a.arora@oracle.com> <20241009165411.3426937-3-ankur.a.arora@oracle.com> <20241009180117.GS17263@noisy.programming.kicks-ass.net> <37af80bd-a54f-4ee4-9175-6f0f27b685a0@paulmck-laptop> <20241010063207.xIrynIqO@linutronix.de> <20241010081032.GA17263@noisy.programming.kicks-ass.net> <20241010091326.nK71dG4b@linutronix.de> <878quvamjm.fsf@oracle.com> <20241011075843.WABHhY70@linutronix.de> User-agent: mu4e 1.4.10; emacs 27.2 From: Ankur Arora To: Sebastian Andrzej Siewior Cc: Ankur Arora , Peter Zijlstra , "Paul E. 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I have that exact configuration (PREEMPT_DYANMIC=n, >> PREEMPT_LAZY=y, PREEMPT_RCU=n). >> >> Can you share your .config? > > Sent offlist. Thanks. So, I tried the config and your config enables PREEMPT_LAZY=y, PREEMPT_DYNAMIC=n. That forces PREEMPT_RCU=n. If in that config you change the preemption options to PREEMPT_LAZY=y, PREEMPT_DYNAMIC=y, we get PREEMPT_RCU=y. Is that also the behaviour you are seeing? Seems to be doing the right thing. Also, quite similar to how we handle the PREEMPT_NONE/_VOLUNTARY case. And, lazy is meant to have similar preemption behaviour as those models. -- ankur