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    SubjectRe: [PATCHv11 2.6.36-rc2-tip 5/15] 5: uprobes: Uprobes (un)registration and exception handling.
    > On Mon, Sep 06, 2010 at 11:16:42PM +0530, Srikar Dronamraju wrote:
    > > > You don't have to, but you can. The problem I have with this stuff is
    > > > that it makes the pid thing a primary interface, whereas it should be
    > > > one of many filter possibilities.
    > >
    > > I think the otherway,
    > > Why instrument a process and filter it out, if we are not interested in it.
    > > While instrumenting kernel, we dont have this flexibility. So
    > > having a pid based filter is the right thing to do for kernel
    > > based tracing.
    > >
    > > If we can get the per process based tracing right, we can build
    > > higher lever stuff including the file based tracing easily.
    > >
    > > All tools/debuggers in the past have all worked with process based
    > > tracing.
    > I have the feeling that you guys are at least partially talking past
    > each other.
    > For the "perf probe --add" interface the only sane interface is one by
    > filename and then symbol / liner number / etc.

    Agree, probing by file name is a requirement and I am working
    towards that end.
    > But that is just the interface - these probes don't nessecarily have to
    > be armed and cause global overhead once they are define. If the
    > implenmentation is smart enough it will defer arming the probe until
    > we actually use it, and that will be per-process quite often.

    Agree, That why I am trying to build file-based probing on
    pid-based probing.

    > Which btw, brings up two more issues, one in uprobes and one in perf.
    > For one even in userspace I think the dynamic probes will really just
    > be the tip of the iceberg and we'll get more bang for the buck from
    > static traces, which is something that's no supported in uprobes yet.
    > As a start supporting the dtrace-style sdt.h header would be a great
    > help, and then we can decide if we need somthing even better on top.

    Yes, Static tracing using dtrace style sdt.h is a cool thing to do.
    Already SystemTap has this facility. However I think its probably
    better done at perf user interface level.

    The way I look at it is perf probe decodes the static markers and asks
    uprobes to place probepoints over there.
    Do you see a different approach? If yes can you tell what you were
    looking at?

    Thanks and Regards

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