On Thu, 8 Feb 2024 21:18:14 +0800
Huang Yiwei <quic_hyi...@quicinc.com> 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>][,...]]
>
> Also, the sysctl node can handle the input accordingly.
>
> Cc: Ross Zwisler <zwis...@google.com>
> Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org>
> Signed-off-by: Huang Yiwei <quic_hyi...@quicinc.com>
> ---
> .../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
> +
> + 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]
