On Wed, Aug 28, 2019 at 02:26:13PM -0400, Joel Fernandes (Google) wrote: > The dyntick-idle traces are a bit confusing. This patch makes it simpler > and adds some missing cases such as EQS-enter because user vs idle mode. > > Following are the changes: > (1) Add a new context field to trace_rcu_dyntick tracepoint. This > context field can be "USER", "IDLE" or "IRQ". > > (2) Remove the "++=" and "--=" strings and replace them with > "StillNonIdle". This is much easier on the eyes, and the -- and ++ > are easily apparent in the dynticks_nesting counters we are printing > anyway. > > This patch is based on the previous patches to simplify rcu_dyntick > counters [1] and with these traces, I have verified the counters are > working properly. > > [1] > Link: https://lore.kernel.org/patchwork/patch/1120021/ > Link: https://lore.kernel.org/patchwork/patch/1120022/ > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> Looks plausible to me. Thanx, Paul > --- > include/trace/events/rcu.h | 13 ++++++++----- > kernel/rcu/tree.c | 17 +++++++++++------ > 2 files changed, 19 insertions(+), 11 deletions(-) > > diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h > index 66122602bd08..474c1f7e7104 100644 > --- a/include/trace/events/rcu.h > +++ b/include/trace/events/rcu.h > @@ -449,12 +449,14 @@ TRACE_EVENT_RCU(rcu_fqs, > */ > TRACE_EVENT_RCU(rcu_dyntick, > > - TP_PROTO(const char *polarity, long oldnesting, long newnesting, atomic_t dynticks), > + TP_PROTO(const char *polarity, const char *context, long oldnesting, > + long newnesting, atomic_t dynticks), > > - TP_ARGS(polarity, oldnesting, newnesting, dynticks), > + TP_ARGS(polarity, context, oldnesting, newnesting, dynticks), > > TP_STRUCT__entry( > __field(const char *, polarity) > + __field(const char *, context) > __field(long, oldnesting) > __field(long, newnesting) > __field(int, dynticks) > @@ -462,14 +464,15 @@ TRACE_EVENT_RCU(rcu_dyntick, > > TP_fast_assign( > __entry->polarity = polarity; > + __entry->context = context; > __entry->oldnesting = oldnesting; > __entry->newnesting = newnesting; > __entry->dynticks = atomic_read(&dynticks); > ), > > - TP_printk("%s %lx %lx %#3x", __entry->polarity, > - __entry->oldnesting, __entry->newnesting, > - __entry->dynticks & 0xfff) > + TP_printk("%s %s %lx %lx %#3x", __entry->polarity, > + __entry->context, __entry->oldnesting, __entry->newnesting, > + __entry->dynticks & 0xfff) > ); > > /* > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 1465a3e406f8..1a65919ec800 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -570,7 +570,8 @@ static void rcu_eqs_enter(bool user) > } > > lockdep_assert_irqs_disabled(); > - trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdp->dynticks); > + trace_rcu_dyntick(TPS("Start"), (user ? TPS("USER") : TPS("IDLE")), > + rdp->dynticks_nesting, 0, rdp->dynticks); > WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); > rdp = this_cpu_ptr(&rcu_data); > do_nocb_deferred_wakeup(rdp); > @@ -642,15 +643,17 @@ static __always_inline void rcu_nmi_exit_common(bool irq) > * leave it in non-RCU-idle state. > */ > if (rdp->dynticks_nesting != 1) { > - trace_rcu_dyntick(TPS("--="), rdp->dynticks_nesting, > - rdp->dynticks_nesting - 2, rdp->dynticks); > + trace_rcu_dyntick(TPS("StillNonIdle"), TPS("IRQ"), > + rdp->dynticks_nesting, rdp->dynticks_nesting - 2, > + rdp->dynticks); > WRITE_ONCE(rdp->dynticks_nesting, /* No store tearing. */ > rdp->dynticks_nesting - 2); > return; > } > > /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ > - trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nesting, 0, rdp->dynticks); > + trace_rcu_dyntick(TPS("Start"), TPS("IRQ"), rdp->dynticks_nesting, 0, > + rdp->dynticks); > WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid store tearing. */ > > if (irq) > @@ -733,7 +736,8 @@ static void rcu_eqs_exit(bool user) > rcu_dynticks_task_exit(); > rcu_dynticks_eqs_exit(); > rcu_cleanup_after_idle(); > - trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdp->dynticks); > + trace_rcu_dyntick(TPS("End"), (user ? TPS("USER") : TPS("IDLE")), > + rdp->dynticks_nesting, 1, rdp->dynticks); > WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); > WRITE_ONCE(rdp->dynticks_nesting, 1); > > @@ -825,7 +829,8 @@ static __always_inline void rcu_nmi_enter_common(bool irq) > tick_dep_set_cpu(rdp->cpu, TICK_DEP_BIT_RCU); > } > > - trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="), > + trace_rcu_dyntick(incby == 1 ? TPS("End") : TPS("StillNonIdle"), > + TPS("IRQ"), > rdp->dynticks_nesting, > rdp->dynticks_nesting + incby, rdp->dynticks); > > -- > 2.23.0.187.g17f5b7556c-goog >
