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SubjectRe: [PATCH v3] perf stat: Disable NMI watchdog message on hybrid
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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@linux.intel.com>
> ---
> 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.
>
> 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


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