| Message ID | 20240430091740.1826862-28-vschneid@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | context_tracking, rcu: Spring cleaning renaming | expand |
Le Tue, Apr 30, 2024 at 11:17:31AM +0200, Valentin Schneider a écrit : > The "rcu_dyntick" naming convention has been turned into "rcu_watching" for > all helpers now, align the trace event to that. > > To add to the confusion, the strings passed to the trace event are now > reversed: when RCU "starts" the dyntick / EQS state, it "stops" watching. > > Signed-off-by: Valentin Schneider <vschneid@redhat.com> > --- > include/trace/events/rcu.h | 16 ++++++++-------- > kernel/context_tracking.c | 10 +++++----- > 2 files changed, 13 insertions(+), 13 deletions(-) > > diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h > index 4066b6d51e46a..e51ef658437f0 100644 > --- a/include/trace/events/rcu.h > +++ b/include/trace/events/rcu.h > @@ -466,40 +466,40 @@ TRACE_EVENT(rcu_stall_warning, > /* > * Tracepoint for dyntick-idle entry/exit events. These take 2 strings > * as argument: > - * polarity: "Start", "End", "StillNonIdle" for entering, exiting or still not > + * polarity: "Start", "End", "StillWatching" for entering, exiting or still not I can't find StillWathing used below. > * being in dyntick-idle mode. s/dyntick-idle/eqs > * context: "USER" or "IDLE" or "IRQ". > * NMIs nested in IRQs are inferred with nesting > 1 in IRQ context. > * > * These events also take a pair of numbers, which indicate the nesting > * depth before and after the event of interest, and a third number that is > - * the ->dynticks counter. Note that task-related and interrupt-related > + * the RCU_WATCHING counter. Note that task-related and interrupt-related > * events use two separate counters, and that the "++=" and "--=" events > * for irq/NMI will change the counter by two, otherwise by one. > */ > -TRACE_EVENT_RCU(rcu_dyntick, > +TRACE_EVENT_RCU(rcu_watching, > > - TP_PROTO(const char *polarity, long oldnesting, long newnesting, int dynticks), > + TP_PROTO(const char *polarity, long oldnesting, long newnesting, int counter), > > - TP_ARGS(polarity, oldnesting, newnesting, dynticks), > + TP_ARGS(polarity, oldnesting, newnesting, counter), > > TP_STRUCT__entry( > __field(const char *, polarity) > __field(long, oldnesting) > __field(long, newnesting) > - __field(int, dynticks) > + __field(int, counter) > ), > > TP_fast_assign( > __entry->polarity = polarity; > __entry->oldnesting = oldnesting; > __entry->newnesting = newnesting; > - __entry->dynticks = dynticks; > + __entry->counter = counter; > ), > > TP_printk("%s %lx %lx %#3x", __entry->polarity, > __entry->oldnesting, __entry->newnesting, > - __entry->dynticks & 0xfff) > + __entry->counter & 0xfff) > ); > > /* > diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c > index dfa64f21d900d..fdbb584b8e797 100644 > --- a/kernel/context_tracking.c > +++ b/kernel/context_tracking.c > @@ -137,7 +137,7 @@ static void noinstr ct_kernel_exit(bool user, int offset) > > instrumentation_begin(); > lockdep_assert_irqs_disabled(); > - trace_rcu_dyntick(TPS("Start"), ct_nesting(), 0, ct_rcu_watching()); > + trace_rcu_watching(TPS("End"), ct_nesting(), 0, ct_rcu_watching()); > WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); > rcu_preempt_deferred_qs(current); > > @@ -182,7 +182,7 @@ static void noinstr ct_kernel_enter(bool user, int offset) > // instrumentation for the noinstr ct_kernel_enter_state() > instrument_atomic_write(&ct->state, sizeof(ct->state)); > > - trace_rcu_dyntick(TPS("End"), ct_nesting(), 1, ct_rcu_watching()); > + trace_rcu_watching(TPS("Start"), ct_nesting(), 1, ct_rcu_watching()); > WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); > WRITE_ONCE(ct->nesting, 1); > WARN_ON_ONCE(ct_nmi_nesting()); > @@ -219,7 +219,7 @@ void noinstr ct_nmi_exit(void) > * leave it in non-RCU-idle state. > */ > if (ct_nmi_nesting() != 1) { > - trace_rcu_dyntick(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2, > + trace_rcu_watching(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2, > ct_rcu_watching()); > WRITE_ONCE(ct->nmi_nesting, /* No store tearing. */ > ct_nmi_nesting() - 2); > @@ -228,7 +228,7 @@ void noinstr ct_nmi_exit(void) > } > > /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ > - trace_rcu_dyntick(TPS("Startirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); > + trace_rcu_watching(TPS("Endirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); Ah the initial string was wrong and you're fixing it, right? Should be a seperate patch? > WRITE_ONCE(ct->nmi_nesting, 0); /* Avoid store tearing. */ > > // instrumentation for the noinstr ct_kernel_exit_state() > @@ -294,7 +294,7 @@ void noinstr ct_nmi_enter(void) > instrumentation_begin(); > } > > - trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="), > + trace_rcu_watching(incby == 1 ? TPS("Startirq") : TPS("++="), Ditto? Thanks. > ct_nmi_nesting(), > ct_nmi_nesting() + incby, ct_rcu_watching()); > instrumentation_end(); > -- > 2.43.0 >
On 08/05/24 15:59, Frederic Weisbecker wrote: > Le Tue, Apr 30, 2024 at 11:17:31AM +0200, Valentin Schneider a écrit : >> @@ -228,7 +228,7 @@ void noinstr ct_nmi_exit(void) >> } >> >> /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ >> - trace_rcu_dyntick(TPS("Startirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); >> + trace_rcu_watching(TPS("Endirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); > > Ah the initial string was wrong and you're fixing it, right? > > Should be a seperate patch? > No, I'm just creating confusion for everyone involved (including myself) :( Dynticks start when RCU stops watching, so the naming logic gets flipped on its head. If I take the original comment from bd2b879a1ca5 ("rcu: Add tracing to irq/NMI dyntick-idle transitions") """ as argument: "Start" for entering dyntick-idle mode, "Startirq" for entering it from irq/NMI """ So here "Startirq" means "start dyntick mode from IRQ". With the name change, it should be "Endirq", since RCU stops watching, from IRQ... I know, a lot of confusion for 0 functional change :(
Le Mon, May 13, 2024 at 08:40:42PM +0200, Valentin Schneider a écrit : > On 08/05/24 15:59, Frederic Weisbecker wrote: > > Le Tue, Apr 30, 2024 at 11:17:31AM +0200, Valentin Schneider a écrit : > >> @@ -228,7 +228,7 @@ void noinstr ct_nmi_exit(void) > >> } > >> > >> /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ > >> - trace_rcu_dyntick(TPS("Startirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); > >> + trace_rcu_watching(TPS("Endirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); > > > > Ah the initial string was wrong and you're fixing it, right? > > > > Should be a seperate patch? > > > > No, I'm just creating confusion for everyone involved (including myself) :( > Dynticks start when RCU stops watching, so the naming logic gets flipped on > its head. > > If I take the original comment from > bd2b879a1ca5 ("rcu: Add tracing to irq/NMI dyntick-idle transitions") > """ > as argument: "Start" for entering dyntick-idle mode, "Startirq" for > entering it from irq/NMI > """ Oh my! > > So here "Startirq" means "start dyntick mode from IRQ". With the name > change, it should be "Endirq", since RCU stops watching, from IRQ... > > I know, a lot of confusion for 0 functional change :( Ok your change looks good then. Thanks.
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 4066b6d51e46a..e51ef658437f0 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -466,40 +466,40 @@ TRACE_EVENT(rcu_stall_warning, /* * Tracepoint for dyntick-idle entry/exit events. These take 2 strings * as argument: - * polarity: "Start", "End", "StillNonIdle" for entering, exiting or still not + * polarity: "Start", "End", "StillWatching" for entering, exiting or still not * being in dyntick-idle mode. * context: "USER" or "IDLE" or "IRQ". * NMIs nested in IRQs are inferred with nesting > 1 in IRQ context. * * These events also take a pair of numbers, which indicate the nesting * depth before and after the event of interest, and a third number that is - * the ->dynticks counter. Note that task-related and interrupt-related + * the RCU_WATCHING counter. Note that task-related and interrupt-related * events use two separate counters, and that the "++=" and "--=" events * for irq/NMI will change the counter by two, otherwise by one. */ -TRACE_EVENT_RCU(rcu_dyntick, +TRACE_EVENT_RCU(rcu_watching, - TP_PROTO(const char *polarity, long oldnesting, long newnesting, int dynticks), + TP_PROTO(const char *polarity, long oldnesting, long newnesting, int counter), - TP_ARGS(polarity, oldnesting, newnesting, dynticks), + TP_ARGS(polarity, oldnesting, newnesting, counter), TP_STRUCT__entry( __field(const char *, polarity) __field(long, oldnesting) __field(long, newnesting) - __field(int, dynticks) + __field(int, counter) ), TP_fast_assign( __entry->polarity = polarity; __entry->oldnesting = oldnesting; __entry->newnesting = newnesting; - __entry->dynticks = dynticks; + __entry->counter = counter; ), TP_printk("%s %lx %lx %#3x", __entry->polarity, __entry->oldnesting, __entry->newnesting, - __entry->dynticks & 0xfff) + __entry->counter & 0xfff) ); /* diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index dfa64f21d900d..fdbb584b8e797 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -137,7 +137,7 @@ static void noinstr ct_kernel_exit(bool user, int offset) instrumentation_begin(); lockdep_assert_irqs_disabled(); - trace_rcu_dyntick(TPS("Start"), ct_nesting(), 0, ct_rcu_watching()); + trace_rcu_watching(TPS("End"), ct_nesting(), 0, ct_rcu_watching()); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); rcu_preempt_deferred_qs(current); @@ -182,7 +182,7 @@ static void noinstr ct_kernel_enter(bool user, int offset) // instrumentation for the noinstr ct_kernel_enter_state() instrument_atomic_write(&ct->state, sizeof(ct->state)); - trace_rcu_dyntick(TPS("End"), ct_nesting(), 1, ct_rcu_watching()); + trace_rcu_watching(TPS("Start"), ct_nesting(), 1, ct_rcu_watching()); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); WRITE_ONCE(ct->nesting, 1); WARN_ON_ONCE(ct_nmi_nesting()); @@ -219,7 +219,7 @@ void noinstr ct_nmi_exit(void) * leave it in non-RCU-idle state. */ if (ct_nmi_nesting() != 1) { - trace_rcu_dyntick(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2, + trace_rcu_watching(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2, ct_rcu_watching()); WRITE_ONCE(ct->nmi_nesting, /* No store tearing. */ ct_nmi_nesting() - 2); @@ -228,7 +228,7 @@ void noinstr ct_nmi_exit(void) } /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ - trace_rcu_dyntick(TPS("Startirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); + trace_rcu_watching(TPS("Endirq"), ct_nmi_nesting(), 0, ct_rcu_watching()); WRITE_ONCE(ct->nmi_nesting, 0); /* Avoid store tearing. */ // instrumentation for the noinstr ct_kernel_exit_state() @@ -294,7 +294,7 @@ void noinstr ct_nmi_enter(void) instrumentation_begin(); } - trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="), + trace_rcu_watching(incby == 1 ? TPS("Startirq") : TPS("++="), ct_nmi_nesting(), ct_nmi_nesting() + incby, ct_rcu_watching()); instrumentation_end();
The "rcu_dyntick" naming convention has been turned into "rcu_watching" for all helpers now, align the trace event to that. To add to the confusion, the strings passed to the trace event are now reversed: when RCU "starts" the dyntick / EQS state, it "stops" watching. Signed-off-by: Valentin Schneider <vschneid@redhat.com> --- include/trace/events/rcu.h | 16 ++++++++-------- kernel/context_tracking.c | 10 +++++----- 2 files changed, 13 insertions(+), 13 deletions(-)