Re: [PATCH v5] tracing: Support to dump instance traces by ftrace_dump_on_oops
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2024-02-27 01:45:58
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On Thu, 8 Feb 2024 21:18:14 +0800 Huang Yiwei [off-list ref] wrote:
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
So we need to add that the syntax is: ftrace_dump_on_oops[=[<0|1|2|orig_cpu>,][<instance_name>[=<1|2|orig_cpu>][,...]]
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Also, the sysctl node can handle the input accordingly. Cc: Ross Zwisler <redacted> Signed-off-by: Joel Fernandes (Google) <redacted> Signed-off-by: Huang Yiwei <redacted> --- .../admin-guide/kernel-parameters.txt | 26 ++- Documentation/admin-guide/sysctl/kernel.rst | 30 +++- include/linux/ftrace.h | 4 +- include/linux/kernel.h | 1 + kernel/sysctl.c | 4 +- kernel/trace/trace.c | 156 +++++++++++++----- kernel/trace/trace_selftest.c | 2 +- 7 files changed, 168 insertions(+), 55 deletions(-)diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 31b3a25680d0..3d6ea8e80c2f 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt@@ -1561,12 +1561,28 @@ The above will cause the "foo" tracing instance to trigger a snapshot at the end of boot up. - ftrace_dump_on_oops[=orig_cpu] + ftrace_dump_on_oops[=2(orig_cpu) | =<instance>][,<instance> | + ,<instance>=2(orig_cpu)] [FTRACE] will dump the trace buffers on oops. - If no parameter is passed, ftrace will dump - buffers of all CPUs, but if you pass orig_cpu, it will - dump only the buffer of the CPU that triggered the - oops. + If no parameter is passed, ftrace will dump global + buffers of all CPUs, if you pass 2 or orig_cpu, it + will dump only the buffer of the CPU that triggered + the oops, or the specific instance will be dumped if + its name is passed. Multiple instance dump is also + supported, and instances are separated by commas. Each + instance supports only dump on CPU that triggered the + oops by passing 2 or orig_cpu to it. + + ftrace_dump_on_oops=foo=orig_cpu + + The above will dump only the buffer of "foo" instance + on CPU that triggered the oops. + + ftrace_dump_on_oops,foo,bar=orig_cpu
I believe the above is incorrect. It should be: ftrace_dump_on_oops=foo,bar=orig_cpu And you can add here as well: ftrace_dump_on_oops[=[<0|1|2|orig_cpu>,][<instance_name>[=<1|2|orig_cpu>][,...]] Thanks, --Steve
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+ + The above will dump global buffer on all CPUs, the + buffer of "foo" instance on all CPUs and the buffer + of "bar" instance on CPU that triggered the oops. ftrace_filter=[function-list]