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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-06-18 22:26:31 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-09-28 21:38:13 -0700
commit300df91ca9358f7f09298eec9503c12b32054ef7 (patch)
tree8917e0c2ee94a5385f4968094c0e1d9a7fdc0055 /kernel/rcutree.c
parent29c00b4a1d9e277786120032aa8364631820d863 (diff)
rcu: Event-trace markers for computing RCU CPU utilization
This commit adds the trace_rcu_utilization() marker that is to be used to allow postprocessing scripts compute RCU's CPU utilization, give or take event-trace overhead. Note that we do not include RCU's dyntick-idle interface because event tracing requires RCU protection, which is not available in dyntick-idle mode. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 45dcc2036a1..2a9643bd6ae 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -184,8 +184,10 @@ void rcu_bh_qs(int cpu)
*/
void rcu_note_context_switch(int cpu)
{
+ trace_rcu_utilization("Start context switch");
rcu_sched_qs(cpu);
rcu_preempt_note_context_switch(cpu);
+ trace_rcu_utilization("End context switch");
}
EXPORT_SYMBOL_GPL(rcu_note_context_switch);
@@ -1275,6 +1277,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
*/
void rcu_check_callbacks(int cpu, int user)
{
+ trace_rcu_utilization("Start scheduler-tick");
if (user ||
(idle_cpu(cpu) && rcu_scheduler_active &&
!in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -1308,6 +1311,7 @@ void rcu_check_callbacks(int cpu, int user)
rcu_preempt_check_callbacks(cpu);
if (rcu_pending(cpu))
invoke_rcu_core();
+ trace_rcu_utilization("End scheduler-tick");
}
#ifdef CONFIG_SMP
@@ -1369,10 +1373,14 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
- if (!rcu_gp_in_progress(rsp))
+ trace_rcu_utilization("Start fqs");
+ if (!rcu_gp_in_progress(rsp)) {
+ trace_rcu_utilization("End fqs");
return; /* No grace period in progress, nothing to force. */
+ }
if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) {
rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */
+ trace_rcu_utilization("End fqs");
return; /* Someone else is already on the job. */
}
if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies))
@@ -1421,11 +1429,13 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */
rsp->fqs_need_gp = 0;
rcu_start_gp(rsp, flags); /* releases rnp->lock */
+ trace_rcu_utilization("End fqs");
return;
}
raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
unlock_fqs_ret:
raw_spin_unlock_irqrestore(&rsp->fqslock, flags);
+ trace_rcu_utilization("End fqs");
}
#else /* #ifdef CONFIG_SMP */
@@ -1481,6 +1491,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
*/
static void rcu_process_callbacks(struct softirq_action *unused)
{
+ trace_rcu_utilization("Start RCU core");
__rcu_process_callbacks(&rcu_sched_state,
&__get_cpu_var(rcu_sched_data));
__rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
@@ -1488,6 +1499,7 @@ static void rcu_process_callbacks(struct softirq_action *unused)
/* If we are last CPU on way to dyntick-idle mode, accelerate it. */
rcu_needs_cpu_flush();
+ trace_rcu_utilization("End RCU core");
}
/*
@@ -1910,6 +1922,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
+ trace_rcu_utilization("Start CPU hotplug");
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
@@ -1945,6 +1958,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
default:
break;
}
+ trace_rcu_utilization("End CPU hotplug");
return NOTIFY_OK;
}