Messages in this thread | | | Date | Tue, 25 Aug 2009 00:30:56 +0200 | Subject | Re: perf_counters issue with enable_on_exec | From | stephane eranian <> |
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On Mon, Aug 24, 2009 at 11:35 PM, Paul Mackerras<paulus@samba.org> wrote: > stephane eranian writes: > >> I am running into an issue trying to use enable_on_exec >> in per-thread mode with an event group. >> >> My understanding is that enable_on_exec allows activation >> of an event on first exec. This is useful for tools monitoring >> other tasks and which you invoke as: tool my_program. In >> other words, the tool forks+execs my_program. This option >> allows developers to setup the events after the fork (to get >> the pid) but before the exec(). Only execution after the exec >> is monitored. This alleviates the need to use the >> ptrace(PTRACE_TRACEME) call. >> >> My understanding is that an event group is scheduled only >> if all events in the group are active (disabled=0). Thus, one > > Not quite - if the leader is disabled then none of the group goes on. > If the leader is enabled then it and any other group members that are > enabled go on. If a non-leader member is disabled then it doesn't go > on but it doesn't stop other members from going on. > okay, what is not clear to me is why you need that level of granularity? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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