Messages in this thread Patch in this message | | | Date | Mon, 18 Oct 2010 16:29:46 -0400 | From | Steven Rostedt <> | Subject | [PATCH 7/7] tracing: Remove parent recording in latency tracer graph options |
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From: Steven Rostedt <srostedt@redhat.com>
Even though the parent is recorded with the normal function tracing of the latency tracers (irqsoff and wakeup), the function graph recording is bogus.
This is due to the function graph messing with the return stack. The latency tracers pass in as the parent CALLER_ADDR0, which works fine for plain function tracing. But this causes bogus output with the graph tracer:
3) <idle>-0 | d.s3. 0.000 us | return_to_handler(); 3) <idle>-0 | d.s3. 0.000 us | _raw_spin_unlock_irqrestore(); 3) <idle>-0 | d.s3. 0.000 us | return_to_handler(); 3) <idle>-0 | d.s3. 0.000 us | trace_hardirqs_on();
The "return_to_handle()" call is the trampoline of the function graph tracer, and is meaningless in this context.
Cc: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- kernel/trace/trace_functions_graph.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 6f8fe28..76b0598 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -287,7 +287,6 @@ trace_graph_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, int pc) { - __trace_graph_function(tr, parent_ip, flags, pc); __trace_graph_function(tr, ip, flags, pc); } -- 1.7.1
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