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Tue, 20 Feb 2024 13:01:05 -0800 (PST) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id ba1-20020a0560001c0100b0033d67bdce97sm3692599wrb.84.2024.02.20.13.01.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Feb 2024 13:01:04 -0800 (PST) From: Dmitry Safonov To: Steven Rostedt , Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Jonathan Corbet Cc: Dmitry Safonov , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com> Subject: [PATCH] Documentation/ftrace: Correct wording on trace_options sharing Date: Tue, 20 Feb 2024 21:00:57 +0000 Message-ID: <20240220-ftrace-options-docs-v1-1-95448f535056@arista.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.13-dev-b6b4b X-Developer-Signature: v=1; a=ed25519-sha256; t=1708462857; l=2812; i=dima@arista.com; s=20231212; h=from:subject:message-id; bh=c8mj9GCK/VYC0uTtjPPbxdw6XzLVLtkaxBhdmNk2hx0=; b=jXhDaX0neWOtUA+vokXv020wbVW5s7v4qUlz41JpacdByfyFhRhNBHxMSe2s1zii1Go3naEX6 fhLzBLV4kQZAv/CbQHlq6GNX0AzuUqNLt8NlxPhwJ78mYBzRKhH41I/ X-Developer-Key: i=dima@arista.com; a=ed25519; pk=hXINUhX25b0D/zWBKvd6zkvH7W2rcwh/CH6cjEa3OTk= Content-Transfer-Encoding: quoted-printable I'm writing just another net selftest, where I'm planning to check tcp-ao tracepoints. As I want the test to clean up after itself and affect other possible tests as little as possible, I'm creating an ftrace instance with event filters. In order to simplify, going to disable most of trace_options I don't need. And the current wording made me think it's not possible to set per-instance trace_options. And trying that in practice contradicted the documentation: > # echo 1 > events/signal/enable > # cd - > /root/ksft-ftrace-4Py39Z/instances/ksft > # echo 1 > events/signal/enable > # cat trace > # tracer: nop > # > # entries-in-buffer/entries-written: 6/6 #P:2 > # > # TASK-PID CPU# TIMESTAMP FUNCTION > # | | | | | > cat-7568 [000] 491748.118710: signal_generate: sig=3D17 = errno=3D0 code=3D1 comm=3Dbash pid=3D6189 grp=3D1 res=3D0 > bash-6189 [001] 491748.119003: signal_deliver: sig=3D17 e= rrno=3D0 code=3D1 sa_handler=3D55c728d3bce0 sa_flags=3D14000000 > # cd - > /root/ksft-ftrace-4Py39Z/instances/ppp > # cat trace > # tracer: nop > # > JZ=C3=8A<=C2=BFtype: 154 > f>=C3=AF>=C2=BFtype: 154 > -=C2=B8=C3=B3>=C2=BFtype: 153 > vW.A?=C2=BFtype: 154 It seems that since commit 16270145ce6b ("tracing: Add trace options for core options to instances") it is possible to set per-instance trace_options, with an exception to three of them. Document the current state of affairs. Signed-off-by: Dmitry Safonov --- Documentation/trace/ftrace.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 7e7b8ec17934..c79a6bcef3c9 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -3603,9 +3603,9 @@ The files in the new directory work just like the fil= es with the same name in the tracing directory except the buffer that is used is a separate and new buffer. The files affect that buffer but do not affect the main buffer with the exception of trace_options. Currently, -the trace_options affect all instances and the top level buffer -the same, but this may change in future releases. That is, options -may become specific to the instance they reside in. +most of the options are specific to the instance they reside in, but +trace_printk, printk-msg-only and record-cmd are affecting all instances +and the top level buffer, but this may change in future releases. =20 Notice that none of the function tracer files are there, nor is current_tracer and available_tracers. This is because the buffers --- base-commit: b401b621758e46812da61fa58a67c3fd8d91de0d change-id: 20240220-ftrace-options-docs-81ecf05d07e4 Best regards, --=20 Dmitry Safonov