Re: [PATCH v5] tracing: Support to dump instance traces by ftrace_dump_on_oops

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 2/27/2024 9:47 AM, Steven Rostedt wrote:
On Thu, 8 Feb 2024 21:18:14 +0800
Huang Yiwei <quic_hyiwei@xxxxxxxxxxx> 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@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Huang Yiwei <quic_hyiwei@xxxxxxxxxxx>
---
  .../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]




[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]

  Powered by Linux