Re: [PATCH 1/3] perf pt: Mark PT return events as "return"

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, May 24, 2016 at 07:26:19PM +0300, Adrian Hunter escreveu:
> On 24/05/2016 5:57 p.m., Arnaldo Carvalho de Melo wrote:
> > Em Mon, May 23, 2016 at 05:52:23PM -0700, Andi Kleen escreveu:
> > > From: Andi Kleen <ak@linux.intel.com>
> > > 
> > > With perf script --itrace=cr we can synthesize calls and returns out of
> > > a PT log. However both calls and returns are marked with the same event,
> > > called branches. This makes it difficult to read and post process,
> > > because calls and returns are somewhat diffferent.
> > > 
> > > Create a separate return event and mark the returns as return.
> > 
> > Adrian, you voiced some concerns about this patch, are those settled?
> 
> What about beautifying the sample flags i.e. instead of displaying the
> letters interpret them into something more human readable e.g.

Looks like a good idea, but can't this be done on top of what he sent?

- Arnaldo
 
> bc	call
> br	return
> bo	conditional jump
> b	jump
> bci	software interrupt
> bri	return from interrupt
> bcs	system call
> brs	return from system call
> by	asynchronous branch
> bcyi	hardware interrupt
> bA	transaction abort
> bB	trace begin
> bE	trace end
> 
> In Tx (x) can turn up on a number of those too.
> 
> 
> > Can I have your Acked-by, please?
> > 
> > - Arnaldo
> > 
> > > Cc: adrian.hunter@intel.com
> > > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > > ---
> > >   tools/perf/util/intel-pt.c | 53 +++++++++++++++++++++++++++++++++++++++++-----
> > >   1 file changed, 48 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> > > index 137196990012..4f0b1d7adf50 100644
> > > --- a/tools/perf/util/intel-pt.c
> > > +++ b/tools/perf/util/intel-pt.c
> > > @@ -82,9 +82,12 @@ struct intel_pt {
> > >   	u64 instructions_id;
> > > 
> > >   	bool sample_branches;
> > > +	bool sample_returns;
> > >   	u32 branches_filter;
> > >   	u64 branches_sample_type;
> > > +	u64 returns_sample_type;
> > >   	u64 branches_id;
> > > +	u64 returns_id;
> > > 
> > >   	bool sample_transactions;
> > >   	u64 transactions_sample_type;
> > > @@ -960,7 +963,8 @@ static int intel_pt_inject_event(union perf_event *event,
> > >   	return perf_event__synthesize_sample(event, type, 0, sample, swapped);
> > >   }
> > > 
> > > -static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
> > > +static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq,
> > > +					bool is_return)
> > >   {
> > >   	int ret;
> > >   	struct intel_pt *pt = ptq->pt;
> > > @@ -990,8 +994,13 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
> > >   	sample.pid = ptq->pid;
> > >   	sample.tid = ptq->tid;
> > >   	sample.addr = ptq->state->to_ip;
> > > -	sample.id = ptq->pt->branches_id;
> > > -	sample.stream_id = ptq->pt->branches_id;
> > > +	if (is_return) {
> > > +		sample.id = ptq->pt->returns_id;
> > > +		sample.stream_id = ptq->pt->returns_id;
> > > +	} else {
> > > +		sample.id = ptq->pt->branches_id;
> > > +		sample.stream_id = ptq->pt->branches_id;
> > > +	}
> > >   	sample.period = 1;
> > >   	sample.cpu = ptq->cpu;
> > >   	sample.flags = ptq->flags;
> > > @@ -1014,6 +1023,8 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
> > > 
> > >   	if (pt->synth_opts.inject) {
> > >   		ret = intel_pt_inject_event(event, &sample,
> > > +					    is_return ?
> > > +					    pt->returns_sample_type :
> > >   					    pt->branches_sample_type,
> > >   					    pt->synth_needs_swap);
> > >   		if (ret)
> > > @@ -1241,7 +1252,13 @@ static int intel_pt_sample(struct intel_pt_queue *ptq)
> > >   		thread_stack__set_trace_nr(ptq->thread, state->trace_nr);
> > > 
> > >   	if (pt->sample_branches) {
> > > -		err = intel_pt_synth_branch_sample(ptq);
> > > +		err = intel_pt_synth_branch_sample(ptq, false);
> > > +		if (err)
> > > +			return err;
> > > +	}
> > > +
> > > +	if (pt->sample_returns) {
> > > +		err = intel_pt_synth_branch_sample(ptq, true);
> > >   		if (err)
> > >   			return err;
> > >   	}
> > > @@ -1956,7 +1973,33 @@ static int intel_pt_synth_events(struct intel_pt *pt,
> > >   		}
> > >   		pt->sample_branches = true;
> > >   		pt->branches_sample_type = attr.sample_type;
> > > -		pt->branches_id = id;
> > > +		pt->branches_id = id++;
> > > +	}
> > > +	if (pt->synth_opts.returns) {
> > > +		attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
> > > +		attr.sample_period = 1;
> > > +		attr.sample_type |= PERF_SAMPLE_ADDR;
> > > +		attr.sample_type &= ~(u64)PERF_SAMPLE_CALLCHAIN;
> > > +		attr.sample_type &= ~(u64)PERF_SAMPLE_BRANCH_STACK;
> > > +		pr_debug("Synthesizing 'return' event with id %" PRIu64 " sample type %#" PRIx64 "\n",
> > > +			 id, (u64)attr.sample_type);
> > > +		err = intel_pt_synth_event(session, &attr, id);
> > > +		if (err) {
> > > +			pr_err("%s: failed to synthesize 'return' event type\n",
> > > +			       __func__);
> > > +			return err;
> > > +		}
> > > +		pt->sample_returns = true;
> > > +		pt->returns_sample_type = attr.sample_type;
> > > +		pt->returns_id = id;
> > > +		evlist__for_each(evlist, evsel) {
> > > +			if (evsel->id && evsel->id[0] == pt->returns_id) {
> > > +				if (evsel->name)
> > > +					zfree(&evsel->name);
> > > +				evsel->name = strdup("return");
> > > +				break;
> > > +			}
> > > +		}
> > >   	}
> > > 
> > >   	pt->synth_needs_swap = evsel->needs_swap;
> > > --
> > > 2.5.5