rcu: Add grace-period, quiescent-state, and call_rcu trace events
Add trace events to record grace-period start and end, quiescent states,
CPUs noticing grace-period start and end, grace-period initialization,
call_rcu() invocation, tasks blocking in RCU read-side critical sections,
tasks exiting those same critical sections, force_quiescent_state()
detection of dyntick-idle and offline CPUs, CPUs entering and leaving
dyntick-idle mode (except from NMIs), CPUs coming online and going
offline, and CPUs being kicked for staying in dyntick-idle mode for too
long (as in many weeks, even on 32-bit systems).
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu: Add the rcu flavor to callback trace events
The earlier trace events for registering RCU callbacks and for invoking
them did not include the RCU flavor (rcu_bh, rcu_preempt, or rcu_sched).
This commit adds the RCU flavor to those trace events.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 4e24399..7e02829 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -166,6 +166,8 @@
rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
+ if (rdp->passed_quiesc == 0)
+ trace_rcu_grace_period("rcu_sched", rdp->gpnum, "cpuqs");
rdp->passed_quiesc = 1;
}
@@ -175,6 +177,8 @@
rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
+ if (rdp->passed_quiesc == 0)
+ trace_rcu_grace_period("rcu_bh", rdp->gpnum, "cpuqs");
rdp->passed_quiesc = 1;
}
@@ -319,6 +323,7 @@
* trust its state not to change because interrupts are disabled.
*/
if (cpu_is_offline(rdp->cpu)) {
+ trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "ofl");
rdp->offline_fqs++;
return 1;
}
@@ -359,6 +364,7 @@
local_irq_restore(flags);
return;
}
+ trace_rcu_dyntick("Start");
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
smp_mb__before_atomic_inc(); /* See above. */
atomic_inc(&rdtp->dynticks);
@@ -396,6 +402,7 @@
/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
smp_mb__after_atomic_inc(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
+ trace_rcu_dyntick("End");
local_irq_restore(flags);
}
@@ -501,6 +508,7 @@
* of the current RCU grace period.
*/
if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) {
+ trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, "dti");
rdp->dynticks_fqs++;
return 1;
}
@@ -683,6 +691,7 @@
* go looking for one.
*/
rdp->gpnum = rnp->gpnum;
+ trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpustart");
if (rnp->qsmask & rdp->grpmask) {
rdp->qs_pending = 1;
rdp->passed_quiesc = 0;
@@ -746,6 +755,7 @@
/* Remember that we saw this grace-period completion. */
rdp->completed = rnp->completed;
+ trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuend");
/*
* If we were in an extended quiescent state, we may have
@@ -856,6 +866,7 @@
/* Advance to a new grace period and initialize state. */
rsp->gpnum++;
+ trace_rcu_grace_period(rsp->name, rsp->gpnum, "start");
WARN_ON_ONCE(rsp->signaled == RCU_GP_INIT);
rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
@@ -870,6 +881,9 @@
rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */
rcu_start_gp_per_cpu(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
+ trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
+ rnp->level, rnp->grplo,
+ rnp->grphi, rnp->qsmask);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
@@ -906,6 +920,9 @@
if (rnp == rdp->mynode)
rcu_start_gp_per_cpu(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
+ trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
+ rnp->level, rnp->grplo,
+ rnp->grphi, rnp->qsmask);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
@@ -939,6 +956,7 @@
if (gp_duration > rsp->gp_max)
rsp->gp_max = gp_duration;
rsp->completed = rsp->gpnum;
+ trace_rcu_grace_period(rsp->name, rsp->completed, "end");
rsp->signaled = RCU_GP_IDLE;
rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
}
@@ -967,6 +985,10 @@
return;
}
rnp->qsmask &= ~mask;
+ trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
+ mask, rnp->qsmask, rnp->level,
+ rnp->grplo, rnp->grphi,
+ !!rnp->gp_tasks);
if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
/* Other bits still set at this level, so done. */
@@ -1135,11 +1157,20 @@
if (rnp->qsmaskinit != 0) {
if (rnp != rdp->mynode)
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ else
+ trace_rcu_grace_period(rsp->name,
+ rnp->gpnum + 1 -
+ !!(rnp->qsmask & mask),
+ "cpuofl");
break;
}
- if (rnp == rdp->mynode)
+ if (rnp == rdp->mynode) {
+ trace_rcu_grace_period(rsp->name,
+ rnp->gpnum + 1 -
+ !!(rnp->qsmask & mask),
+ "cpuofl");
need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
- else
+ } else
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
mask = rnp->grpmask;
rnp = rnp->parent;
@@ -1226,7 +1257,7 @@
next = list->next;
prefetch(next);
debug_rcu_head_unqueue(list);
- __rcu_reclaim(list);
+ __rcu_reclaim(rsp->name, list);
list = next;
if (++count >= bl)
break;
@@ -1552,6 +1583,12 @@
rdp->nxttail[RCU_NEXT_TAIL] = &head->next;
rdp->qlen++;
+ if (__is_kfree_rcu_offset((unsigned long)func))
+ trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func,
+ rdp->qlen);
+ else
+ trace_rcu_callback(rsp->name, head, rdp->qlen);
+
/* If interrupts were disabled, don't dive into RCU core. */
if (irqs_disabled_flags(flags)) {
local_irq_restore(flags);
@@ -1850,6 +1887,7 @@
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
#endif /* #ifdef CONFIG_NO_HZ */
rdp->cpu = cpu;
+ rdp->rsp = rsp;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
@@ -1898,6 +1936,7 @@
rdp->gpnum = rnp->completed; /* if GP in progress... */
rdp->completed = rnp->completed;
rdp->passed_quiesc_completed = rnp->completed - 1;
+ trace_rcu_grace_period(rsp->name, rdp->gpnum, "cpuonl");
}
raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
rnp = rnp->parent;