Messages in this thread | | | Date | Thu, 29 Feb 2024 17:11:49 +0800 | Subject | Re: [PATCH v5] tracing: Support to dump instance traces by ftrace_dump_on_oops | From | Huang Yiwei <> |
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On 2/27/2024 9:47 AM, Steven Rostedt wrote: > On Thu, 8 Feb 2024 21:18:14 +0800 > Huang Yiwei <quic_hyiwei@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>][,...]] > Yeah, this is much more clear, will update the commit message and kernel docs in new patchset. >> >> Also, the sysctl node can handle the input accordingly. >> >> Cc: Ross Zwisler <zwisler@google.com> >> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> >> Signed-off-by: Huang Yiwei <quic_hyiwei@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 explanation is below, I think it's correct? - "ftrace_dump_on_oops," means global buffer on all CPUs - "foo," means foo instance on all CPUs - "bar=orig_cpu" means bar instance on CPU that triggered the oops.
I'm trying to make the example to cover more possibilities.
Regards, Huang Yiwei >> + >> + 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]
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