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Date: Tue, 4 May 2010 19:06:45 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Tom Zanussi <tzanussi@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
Mike Galbraith <efault@....de>,
Paul Mackerras <paulus@...ba.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 1/3] perf: record TRACE_INFO only if using tracepoints
and SAMPLE_RAW
On Tue, May 04, 2010 at 11:00:05AM -0300, Arnaldo Carvalho de Melo wrote:
> From: Tom Zanussi <tzanussi@...il.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@...il.com>
> Cc: Mike Galbraith <efault@....de>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> LKML-Reference: <1272865861.7932.16.camel@...picana>
> Signed-off-by: Tom Zanussi <tzanussi@...il.com>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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.
> for (i = 0; i < nr_counters; i++) {
> - if (attrs[i].sample_type & PERF_SAMPLE_RAW) {
> + if (attrs[i].sample_type & PERF_SAMPLE_RAW &&
> + attrs[i].type == PERF_TYPE_TRACEPOINT) {
> perf_header__set_feat(&session->header, HEADER_TRACE_INFO);
> break;
> }
In fact now we always have PERF_SAMPLE_RAW for tracepoints.
> @@ -662,19 +663,25 @@ static int __cmd_record(int argc, const char **argv)
> return err;
> }
>
> - err = event__synthesize_tracing_data(output, attrs,
> - nr_counters,
> - process_synthesized_event,
> - session);
> - /*
> - * FIXME err <= 0 here actually means that there were no tracepoints
> - * so its not really an error, just that we don't need to synthesize
> - * anything.
> - * We really have to return this more properly and also propagate
> - * errors that now are calling die()
> - */
> - if (err > 0)
> + if (have_tracepoints(attrs, nr_counters)) {
> + /*
> + * FIXME err <= 0 here actually means that
> + * there were no tracepoints so its not really
> + * an error, just that we don't need to
> + * synthesize anything. We really have to
> + * return this more properly and also
> + * propagate errors that now are calling die()
> + */
> + err = event__synthesize_tracing_data(output, attrs,
> + nr_counters,
> + process_synthesized_event,
> + session);
> + if (err <= 0) {
> + pr_err("Couldn't record tracing data.\n");
> + return err;
> + }
> advance_output(err);
> + }
> }
Now get_tracepoints_path() may be called three times. You are leaking some
memory by doing that as the paths are reallocated without beeing released.
>
> machine = perf_session__find_host_machine(session);
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 79da0e5..2b9f898 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -436,7 +436,6 @@ static int perf_header__adds_write(struct perf_header *self, int fd)
> trace_sec->size = lseek(fd, 0, SEEK_CUR) - trace_sec->offset;
> }
>
> -
> if (perf_header__has_feat(self, HEADER_BUILD_ID)) {
> struct perf_file_section *buildid_sec;
>
> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
> index b8c1f64..fc4ab3f 100644
> --- a/tools/perf/util/parse-events.h
> +++ b/tools/perf/util/parse-events.h
> @@ -13,6 +13,7 @@ struct tracepoint_path {
> };
>
> extern struct tracepoint_path *tracepoint_id_to_path(u64 config);
> +extern bool have_tracepoints(struct perf_event_attr *pattrs, int nb_events);
>
> extern int nr_counters;
>
> diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
> index 30cd9b5..0a1fb9d 100644
> --- a/tools/perf/util/trace-event-info.c
> +++ b/tools/perf/util/trace-event-info.c
> @@ -487,6 +487,11 @@ get_tracepoints_path(struct perf_event_attr *pattrs, int nb_events)
> return nr_tracepoints > 0 ? path.next : NULL;
> }
>
> +bool have_tracepoints(struct perf_event_attr *pattrs, int nb_events)
> +{
> + return get_tracepoints_path(pattrs, nb_events) ? true : false;
> +}
> +
> int read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events)
> {
> char buf[BUFSIZ];
> --
> 1.6.2.5
>
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