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authorFrederic Weisbecker <fweisbec@gmail.com>2010-04-18 19:08:41 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2010-04-21 23:11:42 +0200
commitcecbca96da387428e220e307a9c945e37e2f4d9e (patch)
tree2edefda983658c19a8f2b38ff951a3046597a4f7 /Documentation/kernel-parameters.txt
parentb15c7b1cee119999e9eafcd602d24a595e77adac (diff)
downloadlinux-cecbca96da387428e220e307a9c945e37e2f4d9e.tar.bz2
tracing: Dump either the oops's cpu source or all cpus buffers
The ftrace_dump_on_oops kernel parameter, sysctl and sysrq let one dump every cpu buffers when an oops or panic happens. It's nice when you have few cpus but it may take ages if have many, plus you miss the real origin of the problem in all the cpu traces. Sometimes, all you need is to dump the cpu buffer that triggered the opps, most of the time it is our main interest. This patch modifies ftrace_dump_on_oops to handle this choice. The ftrace_dump_on_oops kernel parameter, when it comes alone, has the same behaviour than before. But ftrace_dump_on_oops=orig_cpu will only dump the buffer of the cpu that oops'ed. Similarly, sysctl kernel.ftrace_dump_on_oops=1 and echo 1 > /proc/sys/kernel/ftrace_dump_on_oops keep their previous behaviour. But setting 2 jumps into cpu origin dump mode. v2: Fix double setup v3: Fix spelling issues reported by Randy Dunlap v4: Also update __ftrace_dump in the selftests Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt6
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e4cbca58536c..ab67b33300fb 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -789,8 +789,12 @@ and is between 256 and 4096 characters. It is defined in the file
as early as possible in order to facilitate early
boot debugging.
- ftrace_dump_on_oops
+ ftrace_dump_on_oops[=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.
ftrace_filter=[function-list]
[FTRACE] Limit the functions traced by the function