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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 <paulmck@linux.vnet.ibm.com>
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 <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney 2009-08-22 13:56:51 -07:00 committed by Ingo Molnar
parent 22f00b69f6
commit a157229cab
6 changed files with 14 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/ia64/xen/time.c
View File

@ -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);

1
include/linux/rcupreempt.h
View File

@ -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(); }

1
include/linux/rcutree.h
View File

@ -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)

10
kernel/rcupreempt.c
View File

@ -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);

5
kernel/rcutree.c
View File

@ -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));

3
kernel/timer.c
View File

@ -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);