Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758487AbaGWXnp (ORCPT ); Wed, 23 Jul 2014 19:43:45 -0400 Received: from mail-lb0-f178.google.com ([209.85.217.178]:41047 "EHLO mail-lb0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758439AbaGWXno (ORCPT ); Wed, 23 Jul 2014 19:43:44 -0400 MIME-Version: 1.0 In-Reply-To: <20140723162851.GA17665@linux.vnet.ibm.com> References: <20140723162851.GA17665@linux.vnet.ibm.com> From: Pranith Kumar Date: Wed, 23 Jul 2014 19:43:12 -0400 Message-ID: Subject: Re: [PATCH RFC tip/core/rcu 1/2] Eliminate redundant rcu_sysidle_state variable To: Paul McKenney Cc: LKML , Ingo Molnar , Lai Jiangshan , Dipankar Sarma , Andrew Morton , Mathieu Desnoyers , Josh Triplett , tglx@linutronix.de, Peter Zijlstra , Steven Rostedt , David Howells , Eric Dumazet , dvhart@linux.intel.com, =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , Oleg Nesterov Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 23, 2014 at 12:28 PM, Paul E. McKenney wrote: > Now that we have rcu_state_p, which references rcu_preempt_state for > TREE_PREEMPT_RCU and rcu_sched_state for TREE_RCU, we don't need a > separate rcu_sysidle_state variable. This commit therefore eliminates > rcu_preempt_state in favor of rcu_state_p. > > Signed-off-by: Paul E. McKenney > Reviewed-by: Pranith Kumar > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 24f5bd54ca9b..e31fa71c4d3a 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -2662,16 +2662,6 @@ static void __maybe_unused rcu_kick_nohz_cpu(int cpu) > > #ifdef CONFIG_NO_HZ_FULL_SYSIDLE > > -/* > - * Define RCU flavor that holds sysidle state. This needs to be the > - * most active flavor of RCU. > - */ > -#ifdef CONFIG_PREEMPT_RCU > -static struct rcu_state *rcu_sysidle_state = &rcu_preempt_state; > -#else /* #ifdef CONFIG_PREEMPT_RCU */ > -static struct rcu_state *rcu_sysidle_state = &rcu_sched_state; > -#endif /* #else #ifdef CONFIG_PREEMPT_RCU */ > - > static int full_sysidle_state; /* Current system-idle state. */ > #define RCU_SYSIDLE_NOT 0 /* Some CPU is not idle. */ > #define RCU_SYSIDLE_SHORT 1 /* All CPUs idle for brief period. */ > @@ -2813,7 +2803,7 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, > * not the flavor of RCU that tracks sysidle state, or if this > * is an offline or the timekeeping CPU, nothing to do. > */ > - if (!*isidle || rdp->rsp != rcu_sysidle_state || > + if (!*isidle || rdp->rsp != rcu_state_p || > cpu_is_offline(rdp->cpu) || rdp->cpu == tick_do_timer_cpu) > return; > if (rcu_gp_in_progress(rdp->rsp)) > @@ -2839,7 +2829,7 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, > */ > static bool is_sysidle_rcu_state(struct rcu_state *rsp) > { > - return rsp == rcu_sysidle_state; > + return rsp == rcu_state_p; > } > > /* > @@ -2917,7 +2907,7 @@ static void rcu_sysidle_cancel(void) > static void rcu_sysidle_report(struct rcu_state *rsp, int isidle, > unsigned long maxj, bool gpkt) > { > - if (rsp != rcu_sysidle_state) > + if (rsp != rcu_state_p) > return; /* Wrong flavor, ignore. */ > if (gpkt && nr_cpu_ids <= CONFIG_NO_HZ_FULL_SYSIDLE_SMALL) > return; /* Running state machine from timekeeping CPU. */ > @@ -2986,13 +2976,12 @@ bool rcu_sys_is_idle(void) > > /* Scan all the CPUs looking for nonidle CPUs. */ > for_each_possible_cpu(cpu) { > - rdp = per_cpu_ptr(rcu_sysidle_state->rda, cpu); > + rdp = per_cpu_ptr(rcu_state_p->rda, cpu); > rcu_sysidle_check_cpu(rdp, &isidle, &maxj); > if (!isidle) > break; > } > - rcu_sysidle_report(rcu_sysidle_state, > - isidle, maxj, false); > + rcu_sysidle_report(rcu_state_p, isidle, maxj, false); > oldrss = rss; > rss = ACCESS_ONCE(full_sysidle_state); > } > @@ -3019,7 +3008,7 @@ bool rcu_sys_is_idle(void) > * provided by the memory allocator. > */ > if (nr_cpu_ids > CONFIG_NO_HZ_FULL_SYSIDLE_SMALL && > - !rcu_gp_in_progress(rcu_sysidle_state) && > + !rcu_gp_in_progress(rcu_state_p) && > !rsh.inuse && xchg(&rsh.inuse, 1) == 0) > call_rcu(&rsh.rh, rcu_sysidle_cb); > return false; > -- Pranith -- 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/