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From: Leo Yan <leo.yan@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>,
	 Mike Leach <mike.leach@linaro.org>,
	James Clark <james.clark@linaro.org>,
	 Anshuman Khandual <anshuman.khandual@arm.com>,
	 Yeoreum Yun <yeoreum.yun@arm.com>, Will Deacon <will@kernel.org>,
	 Mark Rutland <mark.rutland@arm.com>,
	Tamas Petz <tamas.petz@arm.com>,
	 Tamas Zsoldos <tamas.zsoldos@arm.com>,
	 Arnaldo Carvalho de Melo <acme@kernel.org>,
	 Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	 Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
	 linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	 Leo Yan <leo.yan@arm.com>
Subject: [PATCH 08/19] coresight: trbe: Use PERF_AUX_FLAG_PARTIAL instead of PERF_AUX_FLAG_COLLISION
Date: Mon, 01 Dec 2025 11:21:58 +0000	[thread overview]
Message-ID: <20251201-trbe_buffer_refactor_v1-1-v1-8-7da32b076b28@arm.com> (raw)
In-Reply-To: <20251201-trbe_buffer_refactor_v1-1-v1-0-7da32b076b28@arm.com>

When tracing stops, there is no collision with other samples, so using
PERF_AUX_FLAG_COLLISION does not accurately reflect the trace state and
may mislead userspace.

Use PERF_AUX_FLAG_PARTIAL instead to indicate that tracing stopped and
the record may contain gaps.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index b06885a08e082fd34f68d9588518807b5c47c86e..0caa4a6b437a3aa39fc6bcc72a23711b54f7c598 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -669,21 +669,14 @@ static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *hand
 	}
 
 	/*
-	 * Mark the buffer to indicate that there was a WRAP event by
-	 * setting the COLLISION flag. This indicates to the user that
-	 * the TRBE trace collection was stopped without stopping the
-	 * ETE and thus there might be some amount of trace that was
-	 * lost between the time the WRAP was detected and the IRQ
-	 * was consumed by the CPU.
-	 *
-	 * Setting the TRUNCATED flag would move the event to STOPPED
-	 * state unnecessarily, even when there is space left in the
-	 * ring buffer. Using the COLLISION flag doesn't have this side
-	 * effect. We only set TRUNCATED flag when there is no space
-	 * left in the ring buffer.
+	 * Mark the buffer to indicate that the trace is stopped by setting
+	 * the PARTIAL flag. This indicates to the user that the TRBE trace
+	 * collection was stopped without stopping the ETE and thus there
+	 * might be some amount of trace that was lost between the time the
+	 * TRBE event was detected and the IRQ was consumed by the CPU.
 	 */
 	if (!is_trbe_running(trbsr))
-		perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION);
+		perf_aux_output_flag(handle, PERF_AUX_FLAG_PARTIAL);
 
 	if (is_trbe_wrap(trbsr))
 		return TRBE_FAULT_ACT_WRAP;

-- 
2.34.1


  parent reply	other threads:[~2025-12-01 11:22 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-01 11:21 [PATCH 00/19] coresight: trbe: Support trigger and circle buffer modes Leo Yan
2025-12-01 11:21 ` [PATCH 01/19] coresight: trbe: Use helpers for checking errata Leo Yan
2025-12-04 12:08   ` Anshuman Khandual
2025-12-01 11:21 ` [PATCH 02/19] coresight: trbe: Remove redundant disable operation Leo Yan
2025-12-04 12:25   ` Anshuman Khandual
2025-12-01 11:21 ` [PATCH 03/19] coresight: trbe: Remove buffer disabling in trbe_handle_overflow() Leo Yan
2025-12-04 12:31   ` Anshuman Khandual
2025-12-01 11:21 ` [PATCH 04/19] coresight: trbe: Remove set_trbe_disabled() from the enable flow Leo Yan
2025-12-04 12:43   ` Anshuman Khandual
2025-12-04 13:25     ` Leo Yan
2025-12-01 11:21 ` [PATCH 05/19] coresight: trbe: Refactor status clearing Leo Yan
2025-12-04 12:57   ` Anshuman Khandual
2025-12-09 15:29     ` Leo Yan
2025-12-01 11:21 ` [PATCH 06/19] coresight: trbe: Refactor syndrome decoding Leo Yan
2025-12-02 11:06   ` Suzuki K Poulose
2025-12-02 14:24     ` Leo Yan
2025-12-09 13:17     ` James Clark
2025-12-09 16:06       ` Leo Yan
2025-12-05  4:10   ` Anshuman Khandual
2025-12-09 15:57     ` Leo Yan
2025-12-01 11:21 ` [PATCH 07/19] coresight: trbe: Refactor AUX flag setting Leo Yan
2025-12-02 11:15   ` Suzuki K Poulose
2025-12-02 14:21     ` Leo Yan
2025-12-09 13:37   ` James Clark
2025-12-10 15:43     ` Leo Yan
2025-12-12 14:50       ` James Clark
2025-12-12 15:27         ` Leo Yan
2025-12-12 15:52           ` James Clark
2025-12-01 11:21 ` Leo Yan [this message]
2025-12-05  4:28   ` [PATCH 08/19] coresight: trbe: Use PERF_AUX_FLAG_PARTIAL instead of PERF_AUX_FLAG_COLLISION Anshuman Khandual
2025-12-09 13:40     ` James Clark
2025-12-10 16:19       ` Leo Yan
2025-12-01 11:21 ` [PATCH 09/19] coresight: trbe: Add fault action argument to trbe_handle_overflow() Leo Yan
2025-12-01 11:22 ` [PATCH 10/19] coresight: trbe: Always check fault action when updating buffer Leo Yan
2025-12-02 12:00   ` Suzuki K Poulose
2025-12-01 11:22 ` [PATCH 11/19] coresight: trbe: Apply overwrite erratum for only wrap event Leo Yan
2025-12-02 12:05   ` Suzuki K Poulose
2025-12-02 16:56     ` Leo Yan
2025-12-02 17:12       ` Leo Yan
2025-12-01 11:22 ` [PATCH 12/19] coresight: trbe: Calculate size for buffer wrapping Leo Yan
2025-12-01 11:22 ` [PATCH 13/19] coresight: trbe: Remove misleading comment Leo Yan
2025-12-01 11:22 ` [PATCH 14/19] coresight: trbe: Refactor compute_trbe_buffer_limit() Leo Yan
2025-12-01 11:22 ` [PATCH 15/19] coresight: trbe: Add static key for bypassing trigger mode Leo Yan
2025-12-02 12:10   ` Suzuki K Poulose
2025-12-01 11:22 ` [PATCH 16/19] coresight: trbe: Support " Leo Yan
2025-12-01 11:22 ` [PATCH 17/19] coresight: trbe: Enable circle mode for snapshot Leo Yan
2025-12-01 11:22 ` [PATCH 18/19] coresight: trbe: Add kunit tests Leo Yan
2025-12-01 11:22 ` [PATCH 19/19] perf: cs-etm: Set watermark for AUX trace Leo Yan
2025-12-05  4:48   ` Anshuman Khandual
2025-12-09 14:54     ` James Clark
2025-12-10  2:22       ` Anshuman Khandual
2025-12-05  4:53 ` [PATCH 00/19] coresight: trbe: Support trigger and circle buffer modes Anshuman Khandual

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