On Mon, Jan 30, 2012 at 11:11:21AM +0100, Ingo Molnar wrote: > > * Peter Zijlstra <[email protected]> wrote: > > > On Sun, 2012-01-29 at 17:32 +0100, Ingo Molnar wrote: > > > * Andrew Steets <[email protected]> wrote: > > > > > > > On 1/28/12 6:01 AM, Ingo Molnar wrote: > > > > > > > > >> prctl(PR_TASK_PERF_EVENTS_DISABLE) doesn't appear to > > > > >> disable perf event counters. Here is a demonstration > > > > >> program: > > > > > > > > > > btw., what's your usecase? > > > > > > > > I'm trying to profile a small section of a long-running > > > > program. I ran into trouble using call-graph recording > > > > and I thought this might be an alternative way of getting > > > > what I was after. > > > > > > That usecase indeed makes sense. Peter, could we allow this > > > for privileged tasks, depending on the perf_paranoia > > > settings or such? > > > > I really dislike it. The sane way around this would be to > > allow easy self-profiling instead of doing things arse about > > face like that. > > So, what workflow are you suggesting to Andrew? > > I guess we are also hurting from the lack of dwarf stack > backtrace decoding - that would allow the filtering by parent > function without modifying the code. I think Frederic had a > prototype working for 32-bit - any update on that?
I haven't touched that for a while. I would be glad if somebody else could relay me on this work. I think Jiri Olsa has been working on something about Dwarf cfi unwinding with a different approach. Mine was about dumping chunks of stack and regs and do the unwinding on post processing. I think Jiri is doing the unwinding from the event overflow fast path. > > Andrew could work that problem around right now by adding: > > -fno-omit-frame-pointer > > to the build of the utility - that should activate -g and > perf-report's --parent filter should also work fine. > > Thanks, > > Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
