Messages in this thread | | | Date | Fri, 16 Jan 2009 14:08:36 +0100 | From | "Frédéric Weisbecker" <> | Subject | Re: [PATCH 0/2] ftrace: updates to tip |
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2009/1/16 Ingo Molnar <mingo@elte.hu>: > > * Steven Rostedt <rostedt@goodmis.org> wrote: > >> Ingo, >> >> The first patch is critical, and needs to stay with trace_output.c Not >> that critical since trace_output.c is not in mainline yet. >> >> The second patch gives the ability to stack trace functions. I've been >> leery about adding this and still keep it a separate option from the >> "stacktrace" that already exists. This is because when enabled with no >> filtering, the lag between typing and seeing what is typed can be up to >> 10 seconds or more. > > Btw., is this true even if frame pointers are enabled? When frame pointers > are disabled we scan the full kernel stack => that can be quite slow if > every kernel function is traced ;-)
Hi Ingo,
The function tracer selects Frame pointers :-)
Frederic.
>> I made the function stack trace an option attached to the function >> tracer, so it must be enabled after the function tracer has been set. >> This still needs to be updated in ftrace.txt. > > maybe we could drive this via the filter API? Something like: > > echo "*btrfs*:stacktrace" >> set_filter_functions > > Would automatically mean that those functions will all generate > stacktraces too. Note how safe this API is by default: the filter is used > for a narrow scope of functions anwyay. To get it for all kernel functions > one would have to do: > > echo "*:stacktrace" >> set_filter_functions > > Which one cannot do accidentally. > > What do you think? > >> The following patches are in: >> >> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git >> >> branch: tip/devel >> >> >> Lai Jiangshan (1): >> ftrace: fix trace_output >> >> Steven Rostedt (1): >> ftrace: add stack trace to function tracer >> >> ---- >> kernel/trace/trace.c | 26 ++++++++---- >> kernel/trace/trace.h | 7 +++ >> kernel/trace/trace_functions.c | 84 ++++++++++++++++++++++++++++++++++++++++ >> kernel/trace/trace_output.c | 65 +++++++++++++++---------------- >> kernel/trace/trace_output.h | 4 +- >> 5 files changed, 141 insertions(+), 45 deletions(-) > > Pulled into tip/tracing/ftrace, thanks Steve! > > Ingo >
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