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rcu: Convert rcu_grace_period tracepoint to gp_seq

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This commit makes the rcu_grace_period tracepoint use gp_seq instead
of ->gpnum or ->completed.  It also introduces a "cpuofl-bgp" string to
less obscurely indicate when a CPU has gone offline while a grace period
is waiting on it.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-05-01 12:54:11 -07:00
parent ab5e869c1f
commit 477351f782
3 changed files with 29 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/trace/events/rcu.h
View File

@ -52,6 +52,7 @@ TRACE_EVENT(rcu_utilization,
* "cpuqs": CPU passes through a quiescent state.
* "cpuonl": CPU comes online.
* "cpuofl": CPU goes offline.
* "cpuofl-bgp": CPU goes offline while blocking a grace period.
* "reqwait": GP kthread sleeps waiting for grace-period request.
* "reqwaitsig": GP kthread awakened by signal from reqwait state.
* "fqswait": GP kthread waiting until time to force quiescent states.
@ -63,24 +64,24 @@ TRACE_EVENT(rcu_utilization,
*/
TRACE_EVENT(rcu_grace_period,
TP_PROTO(const char *rcuname, unsigned long gpnum, const char *gpevent),
TP_PROTO(const char *rcuname, unsigned long gp_seq, const char *gpevent),
TP_ARGS(rcuname, gpnum, gpevent),
TP_ARGS(rcuname, gp_seq, gpevent),
TP_STRUCT__entry(
__field(const char *, rcuname)
__field(unsigned long, gpnum)
__field(unsigned long, gp_seq)
__field(const char *, gpevent)
),
TP_fast_assign(
__entry->rcuname = rcuname;
__entry->gpnum = gpnum;
__entry->gp_seq = gp_seq;
__entry->gpevent = gpevent;
),
TP_printk("%s %lu %s",
__entry->rcuname, __entry->gpnum, __entry->gpevent)
__entry->rcuname, __entry->gp_seq, __entry->gpevent)
);
/*
@ -753,7 +754,7 @@ TRACE_EVENT(rcu_barrier,
#else /* #ifdef CONFIG_RCU_TRACE */
#define trace_rcu_grace_period(rcuname, gpnum, gpevent) do { } while (0)
#define trace_rcu_grace_period(rcuname, gp_seq, gpevent) do { } while (0)
#define trace_rcu_future_grace_period(rcuname, gpnum, completed, c, \
level, grplo, grphi, event) \
do { } while (0)

43
kernel/rcu/tree.c
View File

@ -234,7 +234,7 @@ void rcu_sched_qs(void)
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
return;
trace_rcu_grace_period(TPS("rcu_sched"),
__this_cpu_read(rcu_sched_data.gpnum),
__this_cpu_read(rcu_sched_data.gp_seq),
TPS("cpuqs"));
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
@ -249,7 +249,7 @@ void rcu_bh_qs(void)
RCU_LOCKDEP_WARN(preemptible(), "rcu_bh_qs() invoked with preemption enabled!!!");
if (__this_cpu_read(rcu_bh_data.cpu_no_qs.s)) {
trace_rcu_grace_period(TPS("rcu_bh"),
__this_cpu_read(rcu_bh_data.gpnum),
__this_cpu_read(rcu_bh_data.gp_seq),
TPS("cpuqs"));
__this_cpu_write(rcu_bh_data.cpu_no_qs.b.norm, false);
}
@ -1615,7 +1615,7 @@ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp,
trace_rcu_this_gp(rnp_root, rdp, c, TPS("NoGPkthread"));
goto unlock_out;
}
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum), TPS("newreq"));
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq), TPS("newreq"));
ret = true; /* Caller must wake GP kthread. */
unlock_out:
/* Push furthest requested GP to leaf node and rcu_data structure. */
@ -1702,9 +1702,9 @@ static bool rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
/* Trace depending on how much we were able to accelerate. */
if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL))
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccWaitCB"));
trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("AccWaitCB"));
else
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB"));
trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("AccReadyCB"));
return ret;
}
@ -1774,7 +1774,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
* go looking for one.
*/
rdp->gpnum = rnp->gpnum;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpustart"));
need_gp = !!(rnp->qsmask & rdp->grpmask);
rdp->cpu_no_qs.b.norm = need_gp;
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_dynticks.rcu_qs_ctr);
@ -1851,7 +1851,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
rcu_seq_start(&rsp->gp_seq);
if (WARN_ON_ONCE(((rnp->completed << RCU_SEQ_CTR_SHIFT) >> RCU_SEQ_CTR_SHIFT) != rcu_seq_ctr(rnp->gp_seq))) /* Catch any ->completed/->gp_seq mismatches. */
pr_info("%s ->completed: %#lx (%#lx) ->gp_seq %#lx (%#lx)\n", __func__, rnp->completed, (rnp->completed << RCU_SEQ_CTR_SHIFT) >> RCU_SEQ_CTR_SHIFT, rnp->gp_seq, rcu_seq_ctr(rnp->gp_seq));
trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start"));
trace_rcu_grace_period(rsp->name, rsp->gp_seq, TPS("start"));
raw_spin_unlock_irq_rcu_node(rnp);
/*
@ -1928,7 +1928,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
if (rnp == rdp->mynode)
(void)__note_gp_changes(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
trace_rcu_grace_period_init(rsp->name, rnp->gp_seq,
rnp->level, rnp->grplo,
rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq_rcu_node(rnp);
@ -2048,7 +2048,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
/* Declare grace period done. */
WRITE_ONCE(rsp->completed, rsp->gpnum);
rcu_seq_end(&rsp->gp_seq);
trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end"));
trace_rcu_grace_period(rsp->name, rsp->gp_seq, TPS("end"));
rsp->gp_state = RCU_GP_IDLE;
/* Check for GP requests since above loop. */
rdp = this_cpu_ptr(rsp->rda);
@ -2061,7 +2061,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
if (!rcu_accelerate_cbs(rsp, rnp, rdp) && needgp) {
WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
rsp->gp_req_activity = jiffies;
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq),
TPS("newreq"));
} else {
WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
@ -2087,7 +2087,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
/* Handle grace-period start. */
for (;;) {
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("reqwait"));
rsp->gp_state = RCU_GP_WAIT_GPS;
swait_event_idle(rsp->gp_wq, READ_ONCE(rsp->gp_flags) &
@ -2100,7 +2100,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("reqwaitsig"));
}
@ -2119,7 +2119,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
jiffies + 3 * j);
}
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("fqswait"));
rsp->gp_state = RCU_GP_WAIT_FQS;
ret = swait_event_idle_timeout(rsp->gp_wq,
@ -2134,12 +2134,12 @@ static int __noreturn rcu_gp_kthread(void *arg)
if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
(gf & RCU_GP_FLAG_FQS)) {
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("fqsstart"));
rcu_gp_fqs(rsp, first_gp_fqs);
first_gp_fqs = false;
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("fqsend"));
cond_resched_tasks_rcu_qs();
WRITE_ONCE(rsp->gp_activity, jiffies);
@ -2158,7 +2158,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum),
READ_ONCE(rsp->gp_seq),
TPS("fqswaitsig"));
ret = 1; /* Keep old FQS timing. */
j = jiffies;
@ -2388,17 +2388,16 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
*/
static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
{
RCU_TRACE(unsigned long mask;)
RCU_TRACE(bool blkd;)
RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda);)
RCU_TRACE(struct rcu_node *rnp = rdp->mynode;)
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return;
RCU_TRACE(mask = rdp->grpmask;)
trace_rcu_grace_period(rsp->name,
rnp->gpnum + 1 - !!(rnp->qsmask & mask),
TPS("cpuofl"));
RCU_TRACE(blkd = !!(rnp->qsmask & rdp->grpmask);)
trace_rcu_grace_period(rsp->name, rnp->gp_seq,
blkd ? TPS("cpuofl") : TPS("cpuofl-bgp"));
}
/*
@ -3538,7 +3537,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->core_needs_qs = false;
rdp->rcu_iw_pending = false;
rdp->rcu_iw_gp_seq = rnp->gp_seq - 1;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpuonl"));
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}

2
kernel/rcu/tree_plugin.h
View File

@ -301,7 +301,7 @@ static void rcu_preempt_qs(void)
RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_qs() invoked with preemption enabled!!!\n");
if (__this_cpu_read(rcu_data_p->cpu_no_qs.s)) {
trace_rcu_grace_period(TPS("rcu_preempt"),
__this_cpu_read(rcu_data_p->gpnum),
__this_cpu_read(rcu_data_p->gp_seq),
TPS("cpuqs"));
__this_cpu_write(rcu_data_p->cpu_no_qs.b.norm, false);
barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */