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    SubjectRe: [RFC][PATCH] Make ftrace able to trace function return

    * Steven Rostedt <rostedt@goodmis.org> wrote:

    > gcc -c -finstrument-functions traceme.c

    > This is not 5 extra bytes but 27 extra bytes for a total of 32 bytes
    > at every function. Also note that this also adds these calls to
    > inline functions as well. We could easly stop that by adding
    > "notrace" to the inline define (which I've done).
    >
    > But this would make the patching a bit more difficult (not
    > impossible). But it will bloat the image quite a bit.

    yeah, i too knew it was expensive, but didnt realize it's this bloaty.
    It's a non-starter really.

    How reliable can we make Frederic's trampoline approach? Especially
    with the opt-in function filters of dyn-ftrace, there's real value in
    the trampoline approach IMO (we could display real function cost,
    etc.), and the runtime cost should be OK as long we dont probe a ton
    of functions all the time. (and it's optional anyway)

    Ingo


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