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| author | Robert Elliott <elliott@hp.com> | 2014-05-20 17:10:51 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2014-05-20 23:29:32 -0400 |
| commit | 607e3a29203633eaec7334f2f58f9653df788a06 (patch) | |
| tree | f4fc79986cbd5cb935141e47a982f014c1aeadcc /Documentation | |
| parent | ccdb594653b1c0d5b0f3e6f8bf764c544ba0606d (diff) | |
| download | lwn-607e3a29203633eaec7334f2f58f9653df788a06.tar.gz lwn-607e3a29203633eaec7334f2f58f9653df788a06.zip | |
tracing: Add funcgraph_tail option to print function name after closing braces
In the function-graph tracer, add a funcgraph_tail option
to print the function name on all } lines, not just
functions whose first line is no longer in the trace
buffer.
If a function calls other traced functions, its total
time appears on its } line. This change allows grep
to be used to determine the function for which the
line corresponds.
Update Documentation/trace/ftrace.txt to describe
this new option.
Link: http://lkml.kernel.org/p/20140520221041.8359.6782.stgit@beardog.cce.hp.com
Signed-off-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/trace/ftrace.txt | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index bd365988e8d8..2479b2a0c77c 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -2003,6 +2003,32 @@ want, depending on your needs. 360.774530 | 1) 0.594 us | __phys_addr(); +The function name is always displayed after the closing bracket +for a function if the start of that function is not in the +trace buffer. + +Display of the function name after the closing bracket may be +enabled for functions whose start is in the trace buffer, +allowing easier searching with grep for function durations. +It is default disabled. + + hide: echo nofuncgraph-tail > trace_options + show: echo funcgraph-tail > trace_options + + Example with nofuncgraph-tail (default): + 0) | putname() { + 0) | kmem_cache_free() { + 0) 0.518 us | __phys_addr(); + 0) 1.757 us | } + 0) 2.861 us | } + + Example with funcgraph-tail: + 0) | putname() { + 0) | kmem_cache_free() { + 0) 0.518 us | __phys_addr(); + 0) 1.757 us | } /* kmem_cache_free() */ + 0) 2.861 us | } /* putname() */ + You can put some comments on specific functions by using trace_printk() For example, if you want to put a comment inside the __might_sleep() function, you just have to include |