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tracing: Support to dump instance traces by ftrace_dump_on_oops

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Currently ftrace only dumps the global trace buffer on an OOPs. For
debugging a production usecase, instance trace will be helpful to
check specific problems since global trace buffer may be used for
other purposes.

This patch extend the ftrace_dump_on_oops parameter to dump a specific
or multiple trace instances:

  - ftrace_dump_on_oops=0: as before -- don't dump
  - ftrace_dump_on_oops[=1]: as before -- dump the global trace buffer
  on all CPUs
  - ftrace_dump_on_oops=2 or =orig_cpu: as before -- dump the global
  trace buffer on CPU that triggered the oops
  - ftrace_dump_on_oops=<instance_name>: new behavior -- dump the
  tracing instance matching <instance_name>
  - ftrace_dump_on_oops[=2/orig_cpu],<instance1_name>[=2/orig_cpu],
  <instrance2_name>[=2/orig_cpu]: new behavior -- dump the global trace
  buffer and multiple instance buffer on all CPUs, or only dump on CPU
  that triggered the oops if =2 or =orig_cpu is given

Also, the sysctl node can handle the input accordingly.

Link: https://lore.kernel.org/linux-trace-kernel/20240223083126.1817731-1-quic_hyiwei@quicinc.com

Cc: Ross Zwisler <zwisler@google.com>
Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: <mcgrof@kernel.org>
Cc: <keescook@chromium.org>
Cc: <j.granados@samsung.com>
Cc: <mathieu.desnoyers@efficios.com>
Cc: <corbet@lwn.net>
Signed-off-by: Huang Yiwei <quic_hyiwei@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Huang Yiwei
2024-02-23 16:31:26 +08:00
committed by Steven Rostedt (Google)
parent 0bdfb68c84
commit 19f0423fd5
7 changed files with 167 additions and 54 deletions
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28
Documentation/admin-guide/sysctl/kernel.rst
View File

@@ -296,12 +296,30 @@ kernel panic). This will output the contents of the ftrace buffers to
the console. This is very useful for capturing traces that lead to
crashes and outputting them to a serial console.
= ===================================================
0 Disabled (default).
1 Dump buffers of all CPUs.
2 Dump the buffer of the CPU that triggered the oops.
= ===================================================
======================= ===========================================
0 Disabled (default).
1 Dump buffers of all CPUs.
2(orig_cpu) Dump the buffer of the CPU that triggered the
oops.
<instance> Dump the specific instance buffer on all CPUs.
<instance>=2(orig_cpu) Dump the specific instance buffer on the CPU
that triggered the oops.
======================= ===========================================
Multiple instance dump is also supported, and instances are separated
by commas. If global buffer also needs to be dumped, please specify
the dump mode (1/2/orig_cpu) first for global buffer.
So for example to dump "foo" and "bar" instance buffer on all CPUs,
user can::
echo "foo,bar" > /proc/sys/kernel/ftrace_dump_on_oops
To dump global buffer and "foo" instance buffer on all
CPUs along with the "bar" instance buffer on CPU that triggered the
oops, user can::
echo "1,foo,bar=2" > /proc/sys/kernel/ftrace_dump_on_oops
ftrace_enabled, stack_tracer_enabled
====================================