Re: [PATCH 1/3] perf: record TRACE_INFO only if using tracepoints and SAMPLE_RAW

[Frederic Weisbecker <fweisbec@gmail.com>]

On Tue, May 04, 2010 at 10:39:30PM -0500, Tom Zanussi wrote:
> On Tue, 2010-05-04 at 18:18 -0300, Arnaldo Carvalho de Melo wrote:
> > Em Tue, May 04, 2010 at 07:06:45PM +0200, Frederic Weisbecker escreveu:
> > > On Tue, May 04, 2010 at 11:00:05AM -0300, Arnaldo Carvalho de Melo wrote:
> > > > From: Tom Zanussi <tzanussi@gmail.com>
> > > > 
> > > > The current perf code implicitly assumes SAMPLE_RAW means tracepoints
> > > > are being used, but doesn't check for that.  It happily records the
> > > > TRACE_INFO even if SAMPLE_RAW is used without tracepoints, but when the
> > > > perf data is read it won't go any further when it finds TRACE_INFO but
> > > > no tracepoints, and displays misleading errors.
> > > > 
> > > > This adds a check for both in perf-record, and won't record TRACE_INFO
> > > > unless both are true.  This at least allows perf report -D to dump raw
> > > > events, and avoids triggering a misleading error condition in perf
> > > > trace.  It doesn't actually enable the non-tracepoint raw events to be
> > > > displayed in perf trace, since perf trace currently only deals with
> > > > tracepoint events.
> > > > 
> > > > Cc: Frédéric Weisbecker <fweisbec@gmail.com>
> > > > Cc: Mike Galbraith <efault@gmx.de>
> > > > Cc: Paul Mackerras <paulus@samba.org>
> > > > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > > > LKML-Reference: <1272865861.7932.16.camel@tropicana>
> > > > Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
> > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > > ---
> > > >  tools/perf/builtin-record.c        |   35 +++++++++++++++++++++--------------
> > > >  tools/perf/util/header.c           |    1 -
> > > >  tools/perf/util/parse-events.h     |    1 +
> > > >  tools/perf/util/trace-event-info.c |    5 +++++
> > > >  4 files changed, 27 insertions(+), 15 deletions(-)
> > > > 
> > > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > > > index ac989e9..0ff67d1 100644
> > > > --- a/tools/perf/builtin-record.c
> > > > +++ b/tools/perf/builtin-record.c
> > > > @@ -560,11 +560,12 @@ static int __cmd_record(int argc, const char **argv)
> > > >  			return err;
> > > >  	}
> > > >  
> > > > -	if (raw_samples) {
> > > > +	if (raw_samples && have_tracepoints(attrs, nr_counters)) {
> > > >  		perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
> > > >  	} else {
> > > 
> > > 
> > > 
> > > Using get_tracepoints_path() is a bit costly just to check if we use
> > > tracepoints as it allocates and fill the paths.
> > 
> > Can you please send a fix?
> > 
> 
> Yeah, there's a lot of room for improvement here - thanks for pointing
> it out, Frederic.  The patch below should make it better...
> 
> Tom
> 
> From: Tom Zanussi <tzanussi@gmail.com>
> Date: Tue, 4 May 2010 22:20:16 -0500
> Subject: [PATCH] perf/record: simplify TRACE_INFO tracepoint check
> 
> Fix a couple of inefficiencies and redundancies related to
> have_tracepoints() and its use when checking whether to write
> TRACE_INFO.
> 
> First, there's no need to use get_tracepoints_path() in
> have_tracepoints() - we really just want the part that checks whether
> any attributes correspondo to tracepoints.
> 
> Second, we really don't care about raw_samples per se - tracepoints
> are always raw_samples.  In any case, the have_tracepoints() check
> should be sufficient to decide whether or not to write TRACE_INFO.
> 
> Signed-off-by: Tom Zanussi <tzanussi@gmail.com>



Thanks a lot!

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>



> ---
>  tools/perf/builtin-record.c        |   11 +----------
>  tools/perf/util/trace-event-info.c |    8 +++++++-
>  2 files changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 0ff67d1..d3981ac 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -560,17 +560,8 @@ static int __cmd_record(int argc, const char **argv)
>  			return err;
>  	}
>  
> -	if (raw_samples && have_tracepoints(attrs, nr_counters)) {
> +	if (have_tracepoints(attrs, nr_counters))
>  		perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
> -	} else {
> -		for (i = 0; i < nr_counters; i++) {
> -			if (attrs[i].sample_type & PERF_SAMPLE_RAW &&
> -				attrs[i].type == PERF_TYPE_TRACEPOINT) {
> -				perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
> -				break;
> -			}
> -		}
> -	}
>  
>  	atexit(atexit_header);
>  
> diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
> index 0a1fb9d..b157260 100644
> --- a/tools/perf/util/trace-event-info.c
> +++ b/tools/perf/util/trace-event-info.c
> @@ -489,7 +489,13 @@ get_tracepoints_path(struct perf_event_attr *pattrs, int nb_events)
>  
>  bool have_tracepoints(struct perf_event_attr *pattrs, int nb_events)
>  {
> -	return get_tracepoints_path(pattrs, nb_events) ? true : false;
> +	int i;
> +
> +	for (i = 0; i < nb_events; i++)
> +		if (pattrs[i].type == PERF_TYPE_TRACEPOINT)
> +			return true;
> +
> +	return false;
>  }
>  
>  int read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events)
> -- 
> 1.6.4.GIT
> 
> 
> 
> 
>