Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965516AbbEMU6j (ORCPT ); Wed, 13 May 2015 16:58:39 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:42888 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965008AbbEMU6g (ORCPT ); Wed, 13 May 2015 16:58:36 -0400 Date: Wed, 13 May 2015 10:45:05 -0700 From: "Paul E. McKenney" To: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 15/24] rcu: Directly drive RCU_USER_QS from Kconfig Message-ID: <20150513174505.GK6776@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150512223034.GA1396@linux.vnet.ibm.com> <1431469854-3826-1-git-send-email-paulmck@linux.vnet.ibm.com> <1431469854-3826-15-git-send-email-paulmck@linux.vnet.ibm.com> <20150513003750.GA1806@lerouge> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150513003750.GA1806@lerouge> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15051320-0005-0000-0000-00000AC82CD3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4443 Lines: 135 On Wed, May 13, 2015 at 02:37:52AM +0200, Frederic Weisbecker wrote: > On Tue, May 12, 2015 at 03:30:45PM -0700, Paul E. McKenney wrote: > > From: "Paul E. McKenney" > > > > Currently, Kconfig will ask the user whether RCU_USER_QS should be set. > > This is silly because Kconfig already has all the information that it > > needs to set this parameter. This commit therefore directly drives > > the value of RCU_USER_QS via NO_HZ_FULL's "select" statement. > > > > Reported-by: Ingo Molnar > > Signed-off-by: Paul E. McKenney > > Cc: Frederic Weisbecker > > ACK. And we should remove it completely and use NO_HZ_FULL instead. > There won't seem to be more users. Good point! I have queued the patch shown below for 4.3. Thanx, Paul ------------------------------------------------------------------------ rcu: Drop RCU_USER_QS in favor of NO_HZ_FULL The RCU_USER_QS Kconfig parameter is now just a synonym for NO_HZ_FULL, so this commit eliminates RCU_USER_QS, replacing all uses with NO_HZ_FULL. Reported-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 03a899aabd17..18e377b92875 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -307,7 +307,7 @@ static inline void rcu_sysrq_end(void) } #endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */ -#ifdef CONFIG_RCU_USER_QS +#ifdef CONFIG_NO_HZ_FULL void rcu_user_enter(void); void rcu_user_exit(void); #else @@ -315,7 +315,7 @@ static inline void rcu_user_enter(void) { } static inline void rcu_user_exit(void) { } static inline void rcu_user_hooks_switch(struct task_struct *prev, struct task_struct *next) { } -#endif /* CONFIG_RCU_USER_QS */ +#endif /* CONFIG_NO_HZ_FULL */ #ifdef CONFIG_RCU_NOCB_CPU void rcu_init_nohz(void); diff --git a/init/Kconfig b/init/Kconfig index 4c08197044f1..5b8726c10685 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -537,15 +537,6 @@ config RCU_STALL_COMMON config CONTEXT_TRACKING bool -config RCU_USER_QS - bool - help - This option sets hooks on kernel / userspace boundaries and - puts RCU in extended quiescent state when the CPU runs in - userspace. It means that when a CPU runs in userspace, it is - excluded from the global RCU state machine and thus doesn't - try to keep the timer tick on for RCU. - config CONTEXT_TRACKING_FORCE bool "Force context tracking" depends on CONTEXT_TRACKING diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 7651d7dd982c..012cbee9d354 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -696,7 +696,7 @@ void rcu_idle_enter(void) } EXPORT_SYMBOL_GPL(rcu_idle_enter); -#ifdef CONFIG_RCU_USER_QS +#ifdef CONFIG_NO_HZ_FULL /** * rcu_user_enter - inform RCU that we are resuming userspace. * @@ -709,7 +709,7 @@ void rcu_user_enter(void) { rcu_eqs_enter(1); } -#endif /* CONFIG_RCU_USER_QS */ +#endif /* CONFIG_NO_HZ_FULL */ /** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle @@ -823,7 +823,7 @@ void rcu_idle_exit(void) } EXPORT_SYMBOL_GPL(rcu_idle_exit); -#ifdef CONFIG_RCU_USER_QS +#ifdef CONFIG_NO_HZ_FULL /** * rcu_user_exit - inform RCU that we are exiting userspace. * @@ -834,7 +834,7 @@ void rcu_user_exit(void) { rcu_eqs_exit(1); } -#endif /* CONFIG_RCU_USER_QS */ +#endif /* CONFIG_NO_HZ_FULL */ /** * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 579ce1b929af..4008d9f95dd7 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -92,12 +92,10 @@ config NO_HZ_FULL depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS # We need at least one periodic CPU for timekeeping depends on SMP - # RCU_USER_QS dependency depends on HAVE_CONTEXT_TRACKING # VIRT_CPU_ACCOUNTING_GEN dependency depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON - select RCU_USER_QS select RCU_NOCB_CPU select VIRT_CPU_ACCOUNTING_GEN select IRQ_WORK -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/