From a157229cabd6dd8cfa82525fc9bf730c94cc9ac2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 22 Aug 2009 13:56:51 -0700 Subject: [PATCH] rcu: Simplify rcu_pending()/rcu_check_callbacks() API All calls from outside RCU are of the form: if (rcu_pending(cpu)) rcu_check_callbacks(cpu, user); This is silly, instead we put a call to rcu_pending() in rcu_check_callbacks(), and then make the outside calls be to rcu_check_callbacks(). This cuts down on the code a bit and also gives the compiler a better chance of optimizing. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <125097461311-git-send-email-> Signed-off-by: Ingo Molnar --- arch/ia64/xen/time.c | 3 +-- include/linux/rcupreempt.h | 1 - include/linux/rcutree.h | 1 - kernel/rcupreempt.c | 10 ++++++++-- kernel/rcutree.c | 5 ++++- kernel/timer.c | 3 +-- 6 files changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c index fb8332690179..dbeadb9c8e20 100644 --- a/arch/ia64/xen/time.c +++ b/arch/ia64/xen/time.c @@ -133,8 +133,7 @@ consider_steal_time(unsigned long new_itm) account_idle_ticks(blocked); run_local_timers(); - if (rcu_pending(cpu)) - rcu_check_callbacks(cpu, user_mode(get_irq_regs())); + rcu_check_callbacks(cpu, user_mode(get_irq_regs())); scheduler_tick(); run_posix_cpu_timers(p); diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h index 6c9dd9cf8b8e..aff4772fb49e 100644 --- a/include/linux/rcupreempt.h +++ b/include/linux/rcupreempt.h @@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head, extern void __rcu_read_lock(void); extern void __rcu_read_unlock(void); -extern int rcu_pending(int cpu); extern int rcu_needs_cpu(int cpu); #define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 8a0222ce3b13..c739d90f5e68 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -33,7 +33,6 @@ extern void rcu_sched_qs(int cpu); extern void rcu_bh_qs(int cpu); -extern int rcu_pending(int cpu); extern int rcu_needs_cpu(int cpu); static inline void __rcu_read_lock(void) diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c index 7d777c9f394c..0053ce56e326 100644 --- a/kernel/rcupreempt.c +++ b/kernel/rcupreempt.c @@ -159,6 +159,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_dyntick_sched, rcu_dyntick_sched .dynticks = 1, }; +static int rcu_pending(int cpu); + void rcu_sched_qs(int cpu) { struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu); @@ -961,7 +963,10 @@ static void rcu_check_mb(int cpu) void rcu_check_callbacks(int cpu, int user) { unsigned long flags; - struct rcu_data *rdp = RCU_DATA_CPU(cpu); + struct rcu_data *rdp; + + if (!rcu_pending(cpu)) + return; /* if nothing for RCU to do. */ /* * If this CPU took its interrupt from user mode or from the @@ -976,6 +981,7 @@ void rcu_check_callbacks(int cpu, int user) * CPUs to happen after any such write. */ + rdp = RCU_DATA_CPU(cpu); if (user || (idle_cpu(cpu) && !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { @@ -1382,7 +1388,7 @@ int rcu_needs_cpu(int cpu) rdp->waitschedlist != NULL); } -int rcu_pending(int cpu) +static int rcu_pending(int cpu) { struct rcu_data *rdp = RCU_DATA_CPU(cpu); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 7c515082ae84..4ce3adcfa94d 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -111,6 +111,7 @@ static int qhimark = 10000; /* If this many pending, ignore blimit. */ static int qlowmark = 100; /* Once only this many pending, use blimit. */ static void force_quiescent_state(struct rcu_state *rsp, int relaxed); +static int rcu_pending(int cpu); /* * Return the number of RCU-sched batches processed thus far for debug & stats. @@ -974,6 +975,8 @@ static void rcu_do_batch(struct rcu_data *rdp) */ void rcu_check_callbacks(int cpu, int user) { + if (!rcu_pending(cpu)) + return; /* if nothing for RCU to do. */ if (user || (idle_cpu(cpu) && rcu_scheduler_active && !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { @@ -1329,7 +1332,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) * by the current CPU, returning 1 if so. This function is part of the * RCU implementation; it is -not- an exported member of the RCU API. */ -int rcu_pending(int cpu) +static int rcu_pending(int cpu) { return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) || __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)); diff --git a/kernel/timer.c b/kernel/timer.c index a7f07d5a6241..a3d25f415019 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1156,8 +1156,7 @@ void update_process_times(int user_tick) /* Note: this timer irq context must be accounted for as well. */ account_process_tick(p, user_tick); run_local_timers(); - if (rcu_pending(cpu)) - rcu_check_callbacks(cpu, user_tick); + rcu_check_callbacks(cpu, user_tick); printk_tick(); scheduler_tick(); run_posix_cpu_timers(p); -- GitLab