linux-kernel - [tip:perf/core] perf intel-pt: Fix CYC timestamp calculation after OVF

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Date:   Sat, 9 Feb 2019 05:01:31 -0800
From:   tip-bot for Adrian Hunter <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     adrian.hunter@...el.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, jolsa@...hat.com,
        hpa@...or.com, acme@...hat.com
Subject: [tip:perf/core] perf intel-pt: Fix CYC timestamp calculation after
 OVF

Commit-ID:  03997612904866abe7cdcc992784ef65cb3a4b81
Gitweb:     https://git.kernel.org/tip/03997612904866abe7cdcc992784ef65cb3a4b81
Author:     Adrian Hunter <adrian.hunter@...el.com>
AuthorDate: Wed, 6 Feb 2019 12:39:45 +0200
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Wed, 6 Feb 2019 10:27:27 -0300

perf intel-pt: Fix CYC timestamp calculation after OVF

CYC packet timestamp calculation depends upon CBR which was being
cleared upon overflow (OVF). That can cause errors due to failing to
synchronize with sideband events. Even if a CBR change has been lost,
the old CBR is still a better estimate than zero. So remove the clearing
of CBR.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: stable@...r.kernel.org
Link: http://lkml.kernel.org/r/20190206103947.15750-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 1 -
 1 file changed, 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 ecd25cdc1d3e..a54d6c9a4601 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1395,7 +1395,6 @@ static int intel_pt_overflow(struct intel_pt_decoder *decoder)
 {
 	intel_pt_log("ERROR: Buffer overflow\n");
 	intel_pt_clear_tx_flags(decoder);
-	decoder->cbr = 0;
 	decoder->timestamp_insn_cnt = 0;
 	decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
 	decoder->overflow = true;