linux-kernel - Re: [RFC PATCH v4 12/15] perf stat: Handle NMI in hardware-grouping

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Message-ID: <CAP-5=fW2VFA9fdHiiufrDD011gFHGP6dzdRTV7HT-cBQ0HL5sw@mail.gmail.com>
Date: Sat, 23 Mar 2024 22:26:43 -0700
From: Ian Rogers <irogers@...gle.com>
To: weilin.wang@...el.com
Cc: Kan Liang <kan.liang@...ux.intel.com>, Namhyung Kim <namhyung@...nel.org>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Perry Taylor <perry.taylor@...el.com>, 
	Samantha Alt <samantha.alt@...el.com>, Caleb Biggers <caleb.biggers@...el.com>, 
	Mark Rutland <mark.rutland@....com>
Subject: Re: [RFC PATCH v4 12/15] perf stat: Handle NMI in hardware-grouping

On Thu, Feb 8, 2024 at 7:14 PM <weilin.wang@...el.com> wrote:
>
> From: Weilin Wang <weilin.wang@...el.com>
>
> Add an easy nmi watchdog support in grouping. When nmi watchdog is enabled,
> we reduce the total num of events could be assigned to one group by 1. A
> more efficient solution will be added in later.
>
> Signed-off-by: Weilin Wang <weilin.wang@...el.com>

Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  tools/perf/util/metricgroup.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 95d3868819e3..f1eb73957765 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1947,6 +1947,10 @@ static int insert_new_group(struct list_head *head,
>                            size_t num_fixed_counters)
>  {
>         INIT_LIST_HEAD(&new_group->event_head);
> +       if (sysctl__nmi_watchdog_enabled()) {
> +               pr_debug("NMI watchdog is enabled. Reduce num of counters by 1\n");
> +               num_counters -= 1;
> +       }
>         fill_counter_bitmap(new_group->gp_counters, 0, num_counters);
>         fill_counter_bitmap(new_group->fixed_counters, 0, num_fixed_counters);
>         new_group->taken_alone = false;
> --
> 2.42.0
>