From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josht@linux.vnet.ibm.com, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH -tip] v3 Simplify rcu_pending()/rcu_check_callbacks() API
Date: Sat, 22 Aug 2009 13:56:51 -0700 [thread overview]
Message-ID: <125097461311-git-send-email-> (raw)
In-Reply-To: <20090727181401.GA14120@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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 <paulmck@linux.vnet.ibm.com>
---
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 fb83326..dbeadb9 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 6c9dd9c..aff4772 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 8a0222c..c739d90 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 0eef9b7..2ab2146 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 7c51508..4ce3adc 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 a7f07d5..a3d25f4 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);
--
1.5.2.5
next prev parent reply other threads:[~2009-08-22 20:57 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-27 18:14 [PATCH RFC -tip 0/4] v2 RCU cleanups and simplified preemptable RCU Paul E. McKenney
2009-07-27 18:16 ` [PATCH RFC -tip 1/4] v2 Move private definitions from include/linux/rcutree.h to kernel/rcutree.h Paul E. McKenney
2009-07-27 18:16 ` [PATCH RFC -tip 2/4] v2 Renamings to increase RCU clarity Paul E. McKenney
2009-07-27 18:16 ` [PATCH RFC -tip 3/4] v2 Consolidate sparse and lockdep declarations in include/linux/rcupdate.h Paul E. McKenney
2009-07-27 18:16 ` [PATCH RFC -tip 4/4] v2 Merge preemptable-RCU functionality into hierarchical RCU Paul E. McKenney
2009-08-03 8:20 ` [PATCH RFC -tip 0/4] v2 RCU cleanups and simplified preemptable RCU Ingo Molnar
2009-08-03 13:03 ` Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Move private definitions from include/linux/rcutree.h to kernel/rcutree.h Paul E. McKenney
2009-08-23 9:01 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Renamings to increase RCU clarity Paul E. McKenney
2009-08-23 9:01 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-24 7:17 ` [PATCH -tip] v3 " Lai Jiangshan
2009-08-24 15:36 ` Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Consolidate sparse and lockdep declarations in include/linux/rcupdate.h Paul E. McKenney
2009-08-23 9:02 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-23 18:42 ` Ingo Molnar
2009-08-23 19:33 ` Paul E. McKenney
2009-08-23 22:53 ` Paul E. McKenney
2009-08-24 9:28 ` Ingo Molnar
2009-08-24 16:07 ` Paul E. McKenney
2009-08-24 7:34 ` [PATCH -tip] v3 " Lai Jiangshan
2009-08-24 9:00 ` Ingo Molnar
2009-08-24 16:03 ` Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Fix online/offline indication for rcudata.csv trace file Paul E. McKenney
2009-08-23 9:02 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Merge per-RCU-flavor initialization into pre-existing macro Paul E. McKenney
2009-08-23 9:02 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Use debugfs_remove_recursive() simplify code Paul E. McKenney
2009-08-23 9:02 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-22 20:56 ` Paul E. McKenney [this message]
2009-08-23 9:02 ` [tip:core/rcu] rcu: Simplify rcu_pending()/rcu_check_callbacks() API tip-bot for Paul E. McKenney
2009-08-24 7:10 ` [PATCH -tip] v3 " Peter Zijlstra
2009-08-24 15:42 ` Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Merge preemptable-RCU functionality into hierarchical RCU Paul E. McKenney
2009-08-23 9:03 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-22 20:56 ` [PATCH -tip] v3 Remove CONFIG_PREEMPT_RCU Paul E. McKenney
2009-08-23 9:03 ` [tip:core/rcu] rcu: " tip-bot for Paul E. McKenney
2009-08-24 7:21 ` [PATCH RFC -tip 0/4] v3 RCU cleanups and simplified preemptable RCU Peter Zijlstra
2009-08-24 15:59 ` Paul E. McKenney
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