Re: [PATCH v2] perf arm-spe: Report error if set frequency

[James Clark <james.clark@linaro.org>]

On 27/02/2025 8:55 am, 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 1000 -e arm_spe_0// -- sleep 1
>    Arm SPE: Frequency is not supported. Set period with -c option or PMU parameter (-e arm_spe_0/period=NUM/).
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
> 
> Changes from v1:
> - Sugguested users for '-c' option or PMU parameter 'period' in the log
>    (Namhyung)
> 
>   tools/perf/arch/arm64/util/arm-spe.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
> 
> diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
> index 4301181b8e45..4f2833b62ff5 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 +402,14 @@ 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. "
> +				       "Set period with -c option or PMU parameter (-e %s/period=NUM/).\n",
> +				       evsel->pmu->name);
> +				return -EINVAL;
> +			}
>   		}
>   	}
>   

Reviewed-by: James Clark <james.clark@linaro.org>