On Wed, 14 Jun 2017 13:30:59 -0400 Will Hawkins <[email protected]> wrote:
> > When perf profiles a program started by the same command line, it > > disables the events by default and enables them during exec. Please > > see linux/tools/perf/util/evsel.c:perf_evsel__config(). > > > > Thanks, > > Namhyung > > Namhyung, > > I think that this answers a very important question! Thanks for chiming in! Yes. One difference between the design of ftrace and the design of perf, is that, I avoided inserting call backs throughout the kernel. Perf has a few function calls in the exec code. Just grep "perf" in fs/exec.c. There's a few scattered around there. Causing a slight overhead for when perf is not in use. Hmm, I really should remove all perf injections and make them either a tracepoint or generic jumplabels that anything may attach to. Then ftrace could have the same features. And lttng for that matter. -- Steve
