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

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Message-ID: <Z8AOpLW6RSUU09Ns@google.com>
Date: Wed, 26 Feb 2025 23:05:08 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Leo Yan <leo.yan@....com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
	James Clark <james.clark@...aro.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

Hello,

On Mon, Feb 17, 2025 at 08:20:08AM +0000, Leo Yan wrote:
> 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.

Sorry for the late reply.

Isn't it just -c <period> to set period for Arm SPE?  If so, it'd be
better to say that explicitly.

Thanks,
Namhyung

> 
> > ---
> >  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
> >