linux-kernel - [PATCH 51/53] perf intel-pt: Fix CYC timestamp calculation after OVF

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Message-Id: <20190206184903.24054-52-acme@kernel.org>
Date:   Wed,  6 Feb 2019 15:49:01 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jiri Olsa <jolsa@...hat.com>, stable@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 51/53] perf intel-pt: Fix CYC timestamp calculation after OVF

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

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;
-- 
2.20.1