linux-kernel - Re: [PATCH] perf arm-spe: Report error if set frequency

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Message-ID: <20250217082008.GA8144@e132581.arm.com>
Date: Mon, 17 Feb 2025 08:20:08 +0000
From: Leo Yan <leo.yan@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	James Clark <james.clark@...aro.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf arm-spe: Report error if set frequency

On Wed, Feb 05, 2025 at 06:30:09PM +0000, Leo Yan wrote:
> When users set the parameter '-F' to specify frequency for Arm SPE, the
> tool reports error:
> 
>   perf record -F 1000 -e arm_spe_0// -- sleep 1
>   Error:
>   Invalid event (arm_spe_0//) in per-thread mode, enable system wide with '-a'.
> 
> The output logs are confused and it does not give the correct reminding.
> Arm SPE does not support frequency setting given it adopts a statistical
> based approach.
> 
> Alternatively, Arm SPE supports setting period.  This commit adds a
> for frequency setting.  It reports error and reminds users to set period
> instead.
> 
> After:
> 
>   perf record -F 100 -e arm_spe_0// -- sleep 1
>   Arm SPE: Frequency is not supported. Check manual 'man perf-record' on how to set period.
> 
> Signed-off-by: Leo Yan <leo.yan@....com>

Gentle ping.

> ---
>  tools/perf/arch/arm64/util/arm-spe.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
> index 4301181b8e45..baef0812dc19 100644
> --- a/tools/perf/arch/arm64/util/arm-spe.c
> +++ b/tools/perf/arch/arm64/util/arm-spe.c
> @@ -40,6 +40,19 @@ struct arm_spe_recording {
>  	bool			*wrapped;
>  };
>  
> +/* Iterate config list to detect if the "freq" parameter is set */
> +static bool arm_spe_is_set_freq(struct evsel *evsel)
> +{
> +	struct evsel_config_term *term;
> +
> +	list_for_each_entry(term, &evsel->config_terms, list) {
> +		if (term->type == EVSEL__CONFIG_TERM_FREQ)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
>  /*
>   * arm_spe_find_cpus() returns a new cpu map, and the caller should invoke
>   * perf_cpu_map__put() to release the map after use.
> @@ -389,6 +402,13 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
>  				return -EINVAL;
>  			}
>  			opts->full_auxtrace = true;
> +
> +			if (opts->user_freq != UINT_MAX ||
> +			    arm_spe_is_set_freq(evsel)) {
> +				pr_err("Arm SPE: Frequency is not supported. "
> +				       "Check manual 'man perf-record' on how to set period.\n");
> +				return -EINVAL;
> +			}
>  		}
>  	}
>  
> -- 
> 2.34.1
>