Re: [PATCH v3] perf stat: Disable NMI watchdog message on hybrid

[Jiri Olsa]

On Tue, Jul 06, 2021 at 10:19:47AM +0800, Jin, Yao wrote:
> Hi Jiri,
> 
> On 6/10/2021 11:45 AM, Jin Yao wrote:
> > If we run a single workload that only runs on big core, there is always a
> > ugly message about disabling the NMI watchdog because the atom is not
> > counted.
> > 
> > Before:
> > 
> >    # ./perf stat true
> > 
> >     Performance counter stats for 'true':
> > 
> >                  0.43 msec task-clock                #    0.396 CPUs utilized
> >                     0      context-switches          #    0.000 /sec
> >                     0      cpu-migrations            #    0.000 /sec
> >                    45      page-faults               #  103.918 K/sec
> >               639,634      cpu_core/cycles/          #    1.477 G/sec
> >         <not counted>      cpu_atom/cycles/                                              (0.00%)
> >               643,498      cpu_core/instructions/    #    1.486 G/sec
> >         <not counted>      cpu_atom/instructions/                                        (0.00%)
> >               123,715      cpu_core/branches/        #  285.694 M/sec
> >         <not counted>      cpu_atom/branches/                                            (0.00%)
> >                 4,094      cpu_core/branch-misses/   #    9.454 M/sec
> >         <not counted>      cpu_atom/branch-misses/                                       (0.00%)
> > 
> >           0.001092407 seconds time elapsed
> > 
> >           0.001144000 seconds user
> >           0.000000000 seconds sys
> > 
> >    Some events weren't counted. Try disabling the NMI watchdog:
> >            echo 0 > /proc/sys/kernel/nmi_watchdog
> >            perf stat ...
> >            echo 1 > /proc/sys/kernel/nmi_watchdog
> > 
> >    # ./perf stat -e '{cpu_atom/cycles/,msr/tsc/}' true
> > 
> >     Performance counter stats for 'true':
> > 
> >         <not counted>      cpu_atom/cycles/                                              (0.00%)
> >         <not counted>      msr/tsc/                                                      (0.00%)
> > 
> >           0.001904106 seconds time elapsed
> > 
> >           0.001947000 seconds user
> >           0.000000000 seconds sys
> > 
> >    Some events weren't counted. Try disabling the NMI watchdog:
> >            echo 0 > /proc/sys/kernel/nmi_watchdog
> >            perf stat ...
> >            echo 1 > /proc/sys/kernel/nmi_watchdog
> >    The events in group usually have to be from the same PMU. Try reorganizing the group.
> > 
> > Now we disable the NMI watchdog message on hybrid, otherwise there
> > are too many false positives.
> > 
> > After:
> > 
> >    # ./perf stat true
> > 
> >     Performance counter stats for 'true':
> > 
> >                  0.79 msec task-clock                #    0.419 CPUs utilized
> >                     0      context-switches          #    0.000 /sec
> >                     0      cpu-migrations            #    0.000 /sec
> >                    48      page-faults               #   60.889 K/sec
> >               777,692      cpu_core/cycles/          #  986.519 M/sec
> >         <not counted>      cpu_atom/cycles/                                              (0.00%)
> >               669,147      cpu_core/instructions/    #  848.828 M/sec
> >         <not counted>      cpu_atom/instructions/                                        (0.00%)
> >               128,635      cpu_core/branches/        #  163.176 M/sec
> >         <not counted>      cpu_atom/branches/                                            (0.00%)
> >                 4,089      cpu_core/branch-misses/   #    5.187 M/sec
> >         <not counted>      cpu_atom/branch-misses/                                       (0.00%)
> > 
> >           0.001880649 seconds time elapsed
> > 
> >           0.001935000 seconds user
> >           0.000000000 seconds sys
> > 
> >    # ./perf stat -e '{cpu_atom/cycles/,msr/tsc/}' true
> > 
> >     Performance counter stats for 'true':
> > 
> >         <not counted>      cpu_atom/cycles/                                              (0.00%)
> >         <not counted>      msr/tsc/                                                      (0.00%)
> > 
> >           0.000963319 seconds time elapsed
> > 
> >           0.000999000 seconds user
> >           0.000000000 seconds sys
> > 
> > Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
> > ---
> > v3:
> >   - Use evlist__has_hybrid() to check there is at least one hybrid
> >     event in evlist.
> > 
> > v2:
> >   - If the group was mixed with hybrid event and non-hybrid event,
> >     the NMI watchdog message was still reported. V2 adds checking
> >     for hybrid event mixed group.

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

thanks,
jirka

> > 
> >   tools/perf/util/stat-display.c | 9 ++++++---
> >   1 file changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> > index b759dfd633b4..55ae0d1705a9 100644
> > --- a/tools/perf/util/stat-display.c
> > +++ b/tools/perf/util/stat-display.c
> > @@ -19,6 +19,7 @@
> >   #include "util.h"
> >   #include "iostat.h"
> >   #include "pmu-hybrid.h"
> > +#include "evlist-hybrid.h"
> >   #define CNTR_NOT_SUPPORTED	"<not supported>"
> >   #define CNTR_NOT_COUNTED	"<not counted>"
> > @@ -465,9 +466,11 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
> >   			config->csv_sep);
> >   		if (counter->supported) {
> > -			config->print_free_counters_hint = 1;
> > -			if (is_mixed_hw_group(counter))
> > -				config->print_mixed_hw_group_error = 1;
> > +			if (!evlist__has_hybrid(counter->evlist)) {
> > +				config->print_free_counters_hint = 1;
> > +				if (is_mixed_hw_group(counter))
> > +					config->print_mixed_hw_group_error = 1;
> > +			}
> >   		}
> >   		fprintf(config->output, "%-*s%s",
> > 
> 
> Any comments for v3?
> 
> Thanks
> Jin Yao
> 
>