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Wed, 09 Sep 2026 11:28:55 -0700 (PDT) Received: from lvondent-mobl5 ([72.188.211.115]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5c81c506f31sm5399388e0c.11.2026.09.09.11.28.55 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 11:28:55 -0700 (PDT) From: Luiz Augusto von Dentz To: linux-bluetooth@vger.kernel.org Subject: [PATCH BlueZ v1 06/10] doc/btmon: Document the command latency statistics Date: Wed, 9 Sep 2026 14:28:36 -0400 Message-ID: <20260909182840.1289776-7-luiz.dentz@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909182840.1289776-1-luiz.dentz@gmail.com> References: <20260909182840.1289776-1-luiz.dentz@gmail.com> Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Luiz Augusto von Dentz Describe what the command latency measures, why deferred commands are only measured up to their acknowledgement, and how to read the count of commands without a response. The model drafted the text, which the author reviewed against the actual output. Assisted-by: opencode:claude-opus-5 --- doc/btmon.rst | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/doc/btmon.rst b/doc/btmon.rst index c8611ab2e9e7..80c8a8947caf 100644 --- a/doc/btmon.rst +++ b/doc/btmon.rst @@ -591,6 +591,9 @@ Analyze mode reports, for each controller found in the trace: events, ACL, SCO, ISO, vendor diagnostics, system notes, user logs, control messages). +- **Command latency**: How long the controller took to acknowledge + commands, and how many commands were never answered at all. + - **Per-connection statistics**: For each connection handle found: - Connection type (BR-ACL, LE-ACL, BR-SCO, BR-ESCO, LE-ISO) @@ -627,6 +630,30 @@ interference, retransmissions or controller buffer stalls. Comparing the maximum against ``average + deviation`` shows whether the worst case is representative or a one-off outlier. +Command Latency +--------------- + +Command latency is reported per controller:: + + Command latency: 0-215 msec (~55 msec +/- 70 msec) + Commands without response: 3 + +This measures the interval between an HCI command and the ``Command +Complete`` or ``Command Status`` that acknowledges it, so it describes the +responsiveness of the controller itself. + +Commands that are only acknowledged by a ``Command Status`` and complete +much later through a separate event are measured up to the acknowledgement +only. A ``Create Connection`` that takes three seconds to reach its +``Connect Complete`` is waiting on the remote device rather than on the +controller, and including it would swamp both the average and the +deviation. + +``Commands without response`` counts commands that were never acknowledged +at all before the end of the trace. A non-zero value usually means the +capture simply ended with commands in flight, but a persistently high count +points at firmware dropping commands. + Packet Loss ----------- -- 2.55.0