Linux-ARM-Kernel Archive on
 help / color / Atom feed
From: Leo Yan <>
To: Arnaldo Carvalho de Melo <>,
	Mathieu Poirier <>,
	Alexander Shishkin <>,
	Jiri Olsa <>, Namhyung Kim <>,,,
	Coresight ML <>
Cc: Robert Walker <>,
	Mike Leach <>, Leo Yan <>
Subject: [PATCH v3 6/8] perf cs-etm: Treat NO_SYNC element as trace discontinuity
Date: Tue, 11 Dec 2018 15:38:26 +0800
Message-ID: <> (raw)
In-Reply-To: <>

CoreSight tracer driver might insert barrier packet between different
buffers, thus the decoder can spot the boundaries based on the barrier
packet; the decoder is possible to hit a barrier packet and emit a
NO_SYNC element, then the decoder will find a periodic synchronisation
point inside that next trace block that starts trace again but does not
have the TRACE_ON element as indicator - usually because this block of
trace has wrapped the buffer so we have lost the original point that
trace was enabled.

In upper case, it results in the trace stream only inserts the
OCSD_GEN_TRC_ELEM_NO_SYNC element in the middle of tracing stream, but
we don't handle NO_SYNC element properly and at the end users miss to
see the info for trace discontinuity.

Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when
output from the decoder, but both of them indicate the trace data is
discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as trace
discontinuity and generates CS_ETM_DISCONTINUITY packet for it, so
cs-etm can handle discontinuity for this case, finally it saves the last
trace data for previous trace block and restart samples for new block.

Signed-off-by: Leo Yan <>
Reviewed-by: Mathieu Poirier <>
Cc: Mike Leach <>
Cc: Robert Walker <>
 tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
index 1039f364..bee026e 100644
--- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
+++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
@@ -410,7 +410,6 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
-		break;
 		resp = cs_etm_decoder__buffer_discontinuity(decoder,

linux-arm-kernel mailing list

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-11  7:38 [PATCH v3 0/8] perf cs-etm: Correct packets handling Leo Yan
2018-12-11  7:38 ` [PATCH v3 1/8] perf cs-etm: Correct packets swapping in cs_etm__flush() Leo Yan
2018-12-11  7:38 ` [PATCH v3 2/8] perf cs-etm: Avoid stale branch samples when flush packet Leo Yan
2018-12-11  7:38 ` [PATCH v3 3/8] perf cs-etm: Remove unused 'trace_on' in cs_etm_decoder Leo Yan
2018-12-12 18:41   ` Mathieu Poirier
2018-12-11  7:38 ` [PATCH v3 4/8] perf cs-etm: Refactor enumeration cs_etm_sample_type Leo Yan
2018-12-12 18:41   ` Mathieu Poirier
2018-12-11  7:38 ` [PATCH v3 5/8] perf cs-etm: Rename CS_ETM_TRACE_ON to CS_ETM_DISCONTINUITY Leo Yan
2018-12-11  7:38 ` Leo Yan [this message]
2018-12-13 12:38   ` [PATCH v3 6/8] perf cs-etm: Treat NO_SYNC element as trace discontinuity Arnaldo Carvalho de Melo
2018-12-13 12:41     ` Arnaldo Carvalho de Melo
2018-12-13 13:09       ` leo.yan
2018-12-13 13:21         ` Arnaldo Carvalho de Melo
2018-12-13 13:23           ` leo.yan
2018-12-13 13:26           ` Arnaldo Carvalho de Melo
2018-12-13 13:31             ` leo.yan
2018-12-11  7:38 ` [PATCH v3 7/8] perf cs-etm: Treat EO_TRACE " Leo Yan
2018-12-11  7:38 ` [PATCH v3 8/8] perf cs-etm: Generate branch sample for exception packet Leo Yan
2018-12-12 18:45 ` [PATCH v3 0/8] perf cs-etm: Correct packets handling Mathieu Poirier
2018-12-13 13:11   ` Arnaldo Carvalho de Melo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ARM-Kernel Archive on

Archives are clonable:
	git clone --mirror linux-arm-kernel/git/0.git
	git clone --mirror linux-arm-kernel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ \
	public-inbox-index linux-arm-kernel

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone