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rcu: Convert rcu_grace_period tracepoint to gp_seq 

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. * "cpuqs": CPU passes through a quiescent state.
* "cpuonl": CPU comes online. * "cpuonl": CPU comes online.
* "cpuofl": CPU goes offline. * "cpuofl": CPU goes offline.
* "cpuofl-bgp": CPU goes offline while blocking a grace period.
* "reqwait": GP kthread sleeps waiting for grace-period request. * "reqwait": GP kthread sleeps waiting for grace-period request.
* "reqwaitsig": GP kthread awakened by signal from reqwait state. * "reqwaitsig": GP kthread awakened by signal from reqwait state.
* "fqswait": GP kthread waiting until time to force quiescent states. * "fqswait": GP kthread waiting until time to force quiescent states.
@ -63,24 +64,24 @@ TRACE_EVENT(rcu_utilization,
*/ */
TRACE_EVENT(rcu_grace_period, 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( TP_STRUCT__entry(
__field(const char *, rcuname) __field(const char *, rcuname)
__field(unsigned long, gpnum) __field(unsigned long, gp_seq)
__field(const char *, gpevent) __field(const char *, gpevent)
), ),
TP_fast_assign( TP_fast_assign(
__entry->rcuname = rcuname; __entry->rcuname = rcuname;
__entry->gpnum = gpnum; __entry->gp_seq = gp_seq;
__entry->gpevent = gpevent; __entry->gpevent = gpevent;
), ),
TP_printk("%s %lu %s", 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 */ #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, \ #define trace_rcu_future_grace_period(rcuname, gpnum, completed, c, \
level, grplo, grphi, event) \ level, grplo, grphi, event) \
do { } while (0) 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)) if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.s))
return; return;
trace_rcu_grace_period(TPS("rcu_sched"), trace_rcu_grace_period(TPS("rcu_sched"),
__this_cpu_read(rcu_sched_data.gpnum), __this_cpu_read(rcu_sched_data.gp_seq),
TPS("cpuqs")); TPS("cpuqs"));
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false); __this_cpu_write(rcu_sched_data.cpu_no_qs.b.norm, false);
if (!__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp)) 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!!!"); RCU_LOCKDEP_WARN(preemptible(), "rcu_bh_qs() invoked with preemption enabled!!!");
if (__this_cpu_read(rcu_bh_data.cpu_no_qs.s)) { if (__this_cpu_read(rcu_bh_data.cpu_no_qs.s)) {
trace_rcu_grace_period(TPS("rcu_bh"), trace_rcu_grace_period(TPS("rcu_bh"),
__this_cpu_read(rcu_bh_data.gpnum), __this_cpu_read(rcu_bh_data.gp_seq),
TPS("cpuqs")); TPS("cpuqs"));
__this_cpu_write(rcu_bh_data.cpu_no_qs.b.norm, false); __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")); trace_rcu_this_gp(rnp_root, rdp, c, TPS("NoGPkthread"));
goto unlock_out; 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. */ ret = true; /* Caller must wake GP kthread. */
unlock_out: unlock_out:
/* Push furthest requested GP to leaf node and rcu_data structure. */ /* 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. */ /* Trace depending on how much we were able to accelerate. */
if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) 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 else
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB")); trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("AccReadyCB"));
return ret; return ret;
} }
@ -1774,7 +1774,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
* go looking for one. * go looking for one.
*/ */
rdp->gpnum = rnp->gpnum; 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); need_gp = !!(rnp->qsmask & rdp->grpmask);
rdp->cpu_no_qs.b.norm = need_gp; rdp->cpu_no_qs.b.norm = need_gp;
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_dynticks.rcu_qs_ctr); 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); 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. */ 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)); 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); raw_spin_unlock_irq_rcu_node(rnp);
/* /*
@ -1928,7 +1928,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
if (rnp == rdp->mynode) if (rnp == rdp->mynode)
(void)__note_gp_changes(rsp, rnp, rdp); (void)__note_gp_changes(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp); 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->level, rnp->grplo,
rnp->grphi, rnp->qsmask); rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq_rcu_node(rnp); raw_spin_unlock_irq_rcu_node(rnp);
@ -2048,7 +2048,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
/* Declare grace period done. */ /* Declare grace period done. */
WRITE_ONCE(rsp->completed, rsp->gpnum); WRITE_ONCE(rsp->completed, rsp->gpnum);
rcu_seq_end(&rsp->gp_seq); 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; rsp->gp_state = RCU_GP_IDLE;
/* Check for GP requests since above loop. */ /* Check for GP requests since above loop. */
rdp = this_cpu_ptr(rsp->rda); 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) { if (!rcu_accelerate_cbs(rsp, rnp, rdp) && needgp) {
WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT); WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
rsp->gp_req_activity = jiffies; 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")); TPS("newreq"));
} else { } else {
WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT); 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. */ /* Handle grace-period start. */
for (;;) { for (;;) {
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("reqwait")); TPS("reqwait"));
rsp->gp_state = RCU_GP_WAIT_GPS; rsp->gp_state = RCU_GP_WAIT_GPS;
swait_event_idle(rsp->gp_wq, READ_ONCE(rsp->gp_flags) & 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); WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current)); WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("reqwaitsig")); TPS("reqwaitsig"));
} }
@ -2119,7 +2119,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
jiffies + 3 * j); jiffies + 3 * j);
} }
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("fqswait")); TPS("fqswait"));
rsp->gp_state = RCU_GP_WAIT_FQS; rsp->gp_state = RCU_GP_WAIT_FQS;
ret = swait_event_idle_timeout(rsp->gp_wq, 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) || if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
(gf & RCU_GP_FLAG_FQS)) { (gf & RCU_GP_FLAG_FQS)) {
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("fqsstart")); TPS("fqsstart"));
rcu_gp_fqs(rsp, first_gp_fqs); rcu_gp_fqs(rsp, first_gp_fqs);
first_gp_fqs = false; first_gp_fqs = false;
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("fqsend")); TPS("fqsend"));
cond_resched_tasks_rcu_qs(); cond_resched_tasks_rcu_qs();
WRITE_ONCE(rsp->gp_activity, jiffies); WRITE_ONCE(rsp->gp_activity, jiffies);
@ -2158,7 +2158,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
WRITE_ONCE(rsp->gp_activity, jiffies); WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current)); WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name,
READ_ONCE(rsp->gpnum), READ_ONCE(rsp->gp_seq),
TPS("fqswaitsig")); TPS("fqswaitsig"));
ret = 1; /* Keep old FQS timing. */ ret = 1; /* Keep old FQS timing. */
j = jiffies; 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) 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_data *rdp = this_cpu_ptr(rsp->rda);)
RCU_TRACE(struct rcu_node *rnp = rdp->mynode;) RCU_TRACE(struct rcu_node *rnp = rdp->mynode;)
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return; return;
RCU_TRACE(mask = rdp->grpmask;) RCU_TRACE(blkd = !!(rnp->qsmask & rdp->grpmask);)
trace_rcu_grace_period(rsp->name, trace_rcu_grace_period(rsp->name, rnp->gp_seq,
rnp->gpnum + 1 - !!(rnp->qsmask & mask), blkd ? TPS("cpuofl") : TPS("cpuofl-bgp"));
TPS("cpuofl"));
} }
/* /*
@ -3538,7 +3537,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->core_needs_qs = false; rdp->core_needs_qs = false;
rdp->rcu_iw_pending = false; rdp->rcu_iw_pending = false;
rdp->rcu_iw_gp_seq = rnp->gp_seq - 1; 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); 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"); RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_qs() invoked with preemption enabled!!!\n");
if (__this_cpu_read(rcu_data_p->cpu_no_qs.s)) { if (__this_cpu_read(rcu_data_p->cpu_no_qs.s)) {
trace_rcu_grace_period(TPS("rcu_preempt"), trace_rcu_grace_period(TPS("rcu_preempt"),
__this_cpu_read(rcu_data_p->gpnum), __this_cpu_read(rcu_data_p->gp_seq),
TPS("cpuqs")); TPS("cpuqs"));
__this_cpu_write(rcu_data_p->cpu_no_qs.b.norm, false); __this_cpu_write(rcu_data_p->cpu_no_qs.b.norm, false);
barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */ barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */