Messages in this thread | | | Date | Fri, 16 Jan 2009 12:23:45 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 0/2] ftrace: updates to tip |
| |
* 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 ;-)
> 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
| |