[PATCH] perf tools: Fix Intel BTS/PT timestamp handling

[PATCH] perf tools: Fix Intel BTS/PT timestamp handling

[Adrian Hunter]

Events that don't sample the timestamp have a timestamp
value of -1.  Intel BTS and Intel PT processing wasn't
taking that into account.  This is particularly noticeable
with Intel BTS because timestamps are not requested by
default.  Then, if the conversion of -1 to TSC results
in a small number, the processing is unaffected.
However if the conversion results in a big number, then
the data is processed prematurely before relevant sideband
data like mmap events, which in turn results in samples
with unknown dsos.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/util/intel-bts.c | 2 +-
 tools/perf/util/intel-pt.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index dce99cfb1309..ea768625ab5b 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -610,7 +610,7 @@ static int intel_bts_process_event(struct perf_session *session,
 		return -EINVAL;
 	}
 
-	if (sample->time)
+	if (sample->time && sample->time != (u64)-1)
 		timestamp = perf_time_to_tsc(sample->time, &bts->tc);
 	else
 		timestamp = 0;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 2a4a4120473b..a5acd2fe2447 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1450,7 +1450,7 @@ static int intel_pt_process_event(struct perf_session *session,
 		return -EINVAL;
 	}
 
-	if (sample->time)
+	if (sample->time && sample->time != (u64)-1)
 		timestamp = perf_time_to_tsc(sample->time, &pt->tc);
 	else
 		timestamp = 0;
-- 
1.9.1

Re: [PATCH] perf tools: Fix Intel BTS/PT timestamp handling

[Arnaldo Carvalho de Melo]

Em Thu, Aug 20, 2015 at 11:51:32AM +0300, Adrian Hunter escreveu:
> Events that don't sample the timestamp have a timestamp
> value of -1.  Intel BTS and Intel PT processing wasn't
> taking that into account.  This is particularly noticeable
> with Intel BTS because timestamps are not requested by
> default.  Then, if the conversion of -1 to TSC results
> in a small number, the processing is unaffected.
> However if the conversion results in a big number, then
> the data is processed prematurely before relevant sideband
> data like mmap events, which in turn results in samples
> with unknown dsos.

Thanks, since the BTS code is not in, I'm splitting it from here, so
that this one only fixes what is upstream already, i.e. PT, and will
fold the BTS part with the patch introducing BTS,

- Arnaldo
 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
>  tools/perf/util/intel-bts.c | 2 +-
>  tools/perf/util/intel-pt.c  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
> index dce99cfb1309..ea768625ab5b 100644
> --- a/tools/perf/util/intel-bts.c
> +++ b/tools/perf/util/intel-bts.c
> @@ -610,7 +610,7 @@ static int intel_bts_process_event(struct perf_session *session,
>  		return -EINVAL;
>  	}
>  
> -	if (sample->time)
> +	if (sample->time && sample->time != (u64)-1)
>  		timestamp = perf_time_to_tsc(sample->time, &bts->tc);
>  	else
>  		timestamp = 0;
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index 2a4a4120473b..a5acd2fe2447 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -1450,7 +1450,7 @@ static int intel_pt_process_event(struct perf_session *session,
>  		return -EINVAL;
>  	}
>  
> -	if (sample->time)
> +	if (sample->time && sample->time != (u64)-1)
>  		timestamp = perf_time_to_tsc(sample->time, &pt->tc);
>  	else
>  		timestamp = 0;
> -- 
> 1.9.1

[tip:perf/core] perf tools: Fix Intel PT timestamp handling

[tip-bot for Adrian Hunter]

Commit-ID:  81cd60cc29a9c3e92ad6ca167a4764b2c2d2fc04
Gitweb:     http://git.kernel.org/tip/81cd60cc29a9c3e92ad6ca167a4764b2c2d2fc04
Author:     Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Thu, 20 Aug 2015 11:51:32 +0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 21 Aug 2015 10:29:23 -0300

perf tools: Fix Intel PT timestamp handling

Events that don't sample the timestamp have a timestamp value of -1.

Intel PT processing wasn't taking that into account.

This is particularly noticeable with Intel BTS because timestamps are
not requested by default.

Then, if the conversion of -1 to TSC results in a small number, the
processing is unaffected.

However if the conversion results in a big number, then the data is
processed prematurely before relevant sideband data like mmap events,
which in turn results in samples with unknown dsos.

Commiter note:

Since BTS wasn't upstream, I split the patch to fold the BTS part with
the patch introducing it, to avoid having this bug in the commit
history. PT was already upstream, so this patch contains that part.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1440060692-5585-1-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 2a4a412..a5acd2f 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1450,7 +1450,7 @@ static int intel_pt_process_event(struct perf_session *session,
 		return -EINVAL;
 	}
 
-	if (sample->time)
+	if (sample->time && sample->time != (u64)-1)
 		timestamp = perf_time_to_tsc(sample->time, &pt->tc);
 	else
 		timestamp = 0;