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

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Date:	Thu, 20 Aug 2015 16:28:03 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH] perf tools: Fix Intel BTS/PT timestamp handling

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@...el.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
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