Re: [PATCH 1/1] perf arm-spe: Inject SPE samples in perf-inject

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: James Clark <james.clark@arm.com>
Cc: German Gomez <german.gomez@arm.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Leo Yan <leo.yan@linaro.org>, Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] perf arm-spe: Inject SPE samples in perf-inject
Date: Wed, 17 Nov 2021 12:29:43 -0300	[thread overview]
Message-ID: <YZUf5zu4aOfoIhFl@kernel.org> (raw)
In-Reply-To: <5163f41f-2337-6557-ca91-fb2c66738872@arm.com>

Em Mon, Nov 08, 2021 at 08:39:58PM +0000, James Clark escreveu:
> 
> 
> On 05/11/2021 10:41, German Gomez wrote:
> > Inject synthesized SPE samples during perf-inject run.
> > 
> > Signed-off-by: German Gomez <german.gomez@arm.com>
> 
> Reviewed-by: James Clark <james.clark@arm.com>

Next time please expand this explanations a bit more: why should we
inject such samples? Is this enabling some new mode of operation, fixing
something, what is an example of output before this patch and after it?

- Arnaldo

> > ---
> >  tools/perf/util/arm-spe.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> > index 58b7069c5..7054f2315 100644
> > --- a/tools/perf/util/arm-spe.c
> > +++ b/tools/perf/util/arm-spe.c
> > @@ -51,6 +51,7 @@ struct arm_spe {
> >  	u8				timeless_decoding;
> >  	u8				data_queued;
> >  
> > +	u64				sample_type;
> >  	u8				sample_flc;
> >  	u8				sample_llc;
> >  	u8				sample_tlb;
> > @@ -248,6 +249,12 @@ static void arm_spe_prep_sample(struct arm_spe *spe,
> >  	event->sample.header.size = sizeof(struct perf_event_header);
> >  }
> >  
> > +static int arm_spe__inject_event(union perf_event *event, struct perf_sample *sample, u64 type)
> > +{
> > +	event->header.size = perf_event__sample_event_size(sample, type, 0);
> > +	return perf_event__synthesize_sample(event, type, 0, sample);
> > +}
> > +
> >  static inline int
> >  arm_spe_deliver_synth_event(struct arm_spe *spe,
> >  			    struct arm_spe_queue *speq __maybe_unused,
> > @@ -256,6 +263,12 @@ arm_spe_deliver_synth_event(struct arm_spe *spe,
> >  {
> >  	int ret;
> >  
> > +	if (spe->synth_opts.inject) {
> > +		ret = arm_spe__inject_event(event, sample, spe->sample_type);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> >  	ret = perf_session__deliver_synth_event(spe->session, event, sample);
> >  	if (ret)
> >  		pr_err("ARM SPE: failed to deliver event, error %d\n", ret);
> > @@ -920,6 +933,8 @@ arm_spe_synth_events(struct arm_spe *spe, struct perf_session *session)
> >  	else
> >  		attr.sample_type |= PERF_SAMPLE_TIME;
> >  
> > +	spe->sample_type = attr.sample_type;
> > +
> >  	attr.exclude_user = evsel->core.attr.exclude_user;
> >  	attr.exclude_kernel = evsel->core.attr.exclude_kernel;
> >  	attr.exclude_hv = evsel->core.attr.exclude_hv;
> > 

-- 

- Arnaldo