The gp_seq value can come from either of rdp, rsp or rnp. Only the rsp is the global source of truth (most accurate GP info). The rnp can be off by ~1 and the rdp can be off by way more. Add some more context to traces to clarify where it comes from.
Signed-off-by: Joel Fernandes (Google) <[email protected]> --- include/trace/events/rcu.h | 12 ++++++++---- kernel/rcu/tree.c | 32 ++++++++++++++++---------------- kernel/rcu/tree_plugin.h | 2 +- 3 files changed, 25 insertions(+), 21 deletions(-) diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index a6d49864dcc27..cb5363564f7ed 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -68,24 +68,28 @@ TRACE_EVENT(rcu_utilization, */ TRACE_EVENT_RCU(rcu_grace_period, - TP_PROTO(const char *rcuname, unsigned long gp_seq, const char *gpevent), + TP_PROTO(const char *rcuname, const char *gp_seq_src, + unsigned long gp_seq, const char *gpevent), - TP_ARGS(rcuname, gp_seq, gpevent), + TP_ARGS(rcuname, gp_seq_src, gp_seq, gpevent), TP_STRUCT__entry( __field(const char *, rcuname) + __field(const char *, gp_seq_src) __field(unsigned long, gp_seq) __field(const char *, gpevent) ), TP_fast_assign( __entry->rcuname = rcuname; + __entry->gp_seq_src = gp_seq_src; __entry->gp_seq = gp_seq; __entry->gpevent = gpevent; ), - TP_printk("%s %lu %s", - __entry->rcuname, __entry->gp_seq, __entry->gpevent) + TP_printk("%s %s_gp_seq=%lu %s", + __entry->rcuname, __entry->gp_seq_src, + __entry->gp_seq, __entry->gpevent) ); /* diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c61af6a33fbfd..81df1b837dd9d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1334,7 +1334,7 @@ static bool rcu_start_this_gp(struct rcu_node *rnp_start, struct rcu_data *rdp, trace_rcu_this_gp(rnp, rdp, gp_seq_req, TPS("NoGPkthread")); goto unlock_out; } - trace_rcu_grace_period(rcu_state.name, data_race(rcu_state.gp_seq), TPS("newreq")); + trace_rcu_grace_period(rcu_state.name, "rsp", data_race(rcu_state.gp_seq), TPS("newreq")); ret = true; /* Caller must wake GP kthread. */ unlock_out: /* Push furthest requested GP to leaf node and rcu_data structure. */ @@ -1437,9 +1437,9 @@ static bool rcu_accelerate_cbs(struct rcu_node *rnp, struct rcu_data *rdp) /* Trace depending on how much we were able to accelerate. */ if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccWaitCB")); + trace_rcu_grace_period(rcu_state.name, "rdp", rdp->gp_seq, TPS("AccWaitCB")); else - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccReadyCB")); + trace_rcu_grace_period(rcu_state.name, "rdp", rdp->gp_seq, TPS("AccReadyCB")); /* Count CBs for tracing. */ rcu_segcblist_countseq(&rdp->cblist, cbs, gps); @@ -1543,7 +1543,7 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp) if (!offloaded) ret = rcu_advance_cbs(rnp, rdp); /* Advance CBs. */ rdp->core_needs_qs = false; - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuend")); + trace_rcu_grace_period(rcu_state.name, "rdp", rdp->gp_seq, TPS("cpuend")); } else { if (!offloaded) ret = rcu_accelerate_cbs(rnp, rdp); /* Recent CBs. */ @@ -1559,7 +1559,7 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp) * set up to detect a quiescent state, otherwise don't * go looking for one. */ - trace_rcu_grace_period(rcu_state.name, rnp->gp_seq, TPS("cpustart")); + trace_rcu_grace_period(rcu_state.name, "rnp", rnp->gp_seq, TPS("cpustart")); need_qs = !!(rnp->qsmask & rdp->grpmask); rdp->cpu_no_qs.b.norm = need_qs; rdp->core_needs_qs = need_qs; @@ -1660,7 +1660,7 @@ static bool rcu_gp_init(void) /* Record GP times before starting GP, hence rcu_seq_start(). */ rcu_seq_start(&rcu_state.gp_seq); ASSERT_EXCLUSIVE_WRITER(rcu_state.gp_seq); - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("start")); + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("start")); raw_spin_unlock_irq_rcu_node(rnp); /* @@ -1828,7 +1828,7 @@ static void rcu_gp_fqs_loop(void) WRITE_ONCE(rcu_state.jiffies_kick_kthreads, jiffies + (j ? 3 * j : 2)); } - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("fqswait")); rcu_state.gp_state = RCU_GP_WAIT_FQS; ret = swait_event_idle_timeout_exclusive( @@ -1843,7 +1843,7 @@ static void rcu_gp_fqs_loop(void) /* If time for quiescent-state forcing, do it. */ if (!time_after(rcu_state.jiffies_force_qs, jiffies) || (gf & RCU_GP_FLAG_FQS)) { - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("fqsstart")); rcu_gp_fqs(first_gp_fqs); gf = 0; @@ -1851,7 +1851,7 @@ static void rcu_gp_fqs_loop(void) first_gp_fqs = false; gf = rcu_state.cbovld ? RCU_GP_FLAG_OVLD : 0; } - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("fqsend")); cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); @@ -1862,7 +1862,7 @@ static void rcu_gp_fqs_loop(void) cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); WARN_ON(signal_pending(current)); - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("fqswaitsig")); ret = 1; /* Keep old FQS timing. */ j = jiffies; @@ -1945,7 +1945,7 @@ static void rcu_gp_cleanup(void) raw_spin_lock_irq_rcu_node(rnp); /* GP before ->gp_seq update. */ /* Declare grace period done, trace first to use old GP number. */ - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end")); + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("end")); rcu_seq_end(&rcu_state.gp_seq); ASSERT_EXCLUSIVE_WRITER(rcu_state.gp_seq); rcu_state.gp_state = RCU_GP_IDLE; @@ -1962,7 +1962,7 @@ static void rcu_gp_cleanup(void) if ((offloaded || !rcu_accelerate_cbs(rnp, rdp)) && needgp) { WRITE_ONCE(rcu_state.gp_flags, RCU_GP_FLAG_INIT); WRITE_ONCE(rcu_state.gp_req_activity, jiffies); - trace_rcu_grace_period(rcu_state.name, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("newreq")); } else { @@ -1982,7 +1982,7 @@ static int __noreturn rcu_gp_kthread(void *unused) /* Handle grace-period start. */ for (;;) { - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("reqwait")); rcu_state.gp_state = RCU_GP_WAIT_GPS; swait_event_idle_exclusive(rcu_state.gp_wq, @@ -1996,7 +1996,7 @@ static int __noreturn rcu_gp_kthread(void *unused) cond_resched_tasks_rcu_qs(); WRITE_ONCE(rcu_state.gp_activity, jiffies); WARN_ON(signal_pending(current)); - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, + trace_rcu_grace_period(rcu_state.name, "rsp", rcu_state.gp_seq, TPS("reqwaitsig")); } @@ -2240,7 +2240,7 @@ int rcutree_dying_cpu(unsigned int cpu) return 0; blkd = !!(rnp->qsmask & rdp->grpmask); - trace_rcu_grace_period(rcu_state.name, READ_ONCE(rnp->gp_seq), + trace_rcu_grace_period(rcu_state.name, "rsp", READ_ONCE(rnp->gp_seq), blkd ? TPS("cpuofl") : TPS("cpuofl-bgp")); return 0; } @@ -3733,7 +3733,7 @@ int rcutree_prepare_cpu(unsigned int cpu) rdp->core_needs_qs = false; rdp->rcu_iw_pending = false; rdp->rcu_iw_gp_seq = rdp->gp_seq - 1; - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuonl")); + trace_rcu_grace_period(rcu_state.name, "rdp", rdp->gp_seq, TPS("cpuonl")); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); rcu_prepare_kthreads(cpu); rcu_spawn_cpu_nocb_kthread(cpu); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 982fc5be52698..32f761cf16c33 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -262,7 +262,7 @@ static void rcu_qs(void) { RCU_LOCKDEP_WARN(preemptible(), "rcu_qs() invoked with preemption enabled!!!\n"); if (__this_cpu_read(rcu_data.cpu_no_qs.s)) { - trace_rcu_grace_period(TPS("rcu_preempt"), + trace_rcu_grace_period(TPS("rcu_preempt"), "rdp", __this_cpu_read(rcu_data.gp_seq), TPS("cpuqs")); __this_cpu_write(rcu_data.cpu_no_qs.b.norm, false); -- 2.27.0.111.gc72c7da667-goog
