Masami Hiramatsu wrote:
Steven Rostedt wrote:
On Tue, 2010-01-12 at 05:54 +0100, Frederic Weisbecker wrote:
Now what if I want to launch ls and want to profile a function
inside. What can I do with a trace event. I can't create the
probe event based on a pid as I don't know it in advance.
I could give it the ls cmdline and it manages to activate
on the next ls launched. This is racy as another ls can
be launched concurrently.
You make a wrapper script:
#!/bin/sh
add probe to ls with pid $$
exec $*
I do this all the time to limit the function tracer to a specific app.
#!/bin/sh
echo $$ /debug/tracing/set_ftrace_pid
echo function /debug/tracing/current_tracer
exec $*
I recommend you to add below line at the end of the script,
from my experience. :)
echo nop /debug/tracing/current_tracer
Oops, my bad, it doesn't work after exec...
But, it is very important to disable function tracer after
tracing target process.
So, perhaps, below script may work.
#!/bin/sh
(echo $BASHPID /debug/tracing/set_ftrace_pid
echo function /debug/tracing/current_tracer
exec $*)
echo nop /debug/tracing/current_tracer
Thanks,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhira...@redhat.com
