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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Clark Williams <williams@redhat.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Adrian Hunter <adrian.hunter@intel.com>,
	Jiri Olsa <jolsa@redhat.com>,
	stable@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 69/73] perf intel-pt: Fix sample timestamp wrt non-taken branches
Date: Fri, 17 May 2019 16:36:07 -0300
Message-ID: <20190517193611.4974-70-acme@kernel.org> (raw)
In-Reply-To: <20190517193611.4974-1-acme@kernel.org>

From: Adrian Hunter <adrian.hunter@intel.com>

The sample timestamp is updated to ensure that the timestamp represents
the time of the sample and not a branch that the decoder is still
walking towards. The sample timestamp is updated when the decoder
returns, but the decoder does not return for non-taken branches. Update
the sample timestamp then also.

Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample
timestamp") was also a stable fix and appears, for example, in v4.4
stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample
timestamp").

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Fixes: 3f04d98e972b ("perf intel-pt: Improve sample timestamp")
Link: http://lkml.kernel.org/r/20190510124143.27054-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index 9cbd587489bf..f4c3c84b090f 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1318,8 +1318,11 @@ static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 				return 0;
 			}
 			decoder->ip += intel_pt_insn.length;
-			if (!decoder->tnt.count)
+			if (!decoder->tnt.count) {
+				decoder->sample_timestamp = decoder->timestamp;
+				decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
 				return -EAGAIN;
+			}
 			decoder->tnt.payload <<= 1;
 			continue;
 		}
-- 
2.20.1


      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190517193611.4974-1-acme@kernel.org>
2019-05-17 19:36 ` [PATCH 67/73] perf intel-pt: Fix instructions sampling rate Arnaldo Carvalho de Melo
2019-05-17 19:36 ` [PATCH 68/73] perf intel-pt: Fix improved sample timestamp Arnaldo Carvalho de Melo
2019-05-17 19:36 ` Arnaldo Carvalho de Melo [this message]

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