Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934681AbbENA2g (ORCPT ); Wed, 13 May 2015 20:28:36 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:37923 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933196AbbENA1v (ORCPT ); Wed, 13 May 2015 20:27:51 -0400 Date: Thu, 14 May 2015 02:27:48 +0200 From: Frederic Weisbecker To: "Paul E. McKenney" 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: <20150514002747.GA7055@lerouge> 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> <20150513174505.GK6776@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150513174505.GK6776@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4797 Lines: 141 On Wed, May 13, 2015 at 10:45:05AM -0700, Paul E. McKenney wrote: > 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 Excellent! ACK+! Thanks. > > 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/