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    SubjectRe: [RFC PATCH v1 0/2] perf: Support for SDT markers
    On 02/26/2014 01:48 PM, Namhyung Kim wrote:
    > Hi Masami and Hemant,
    >
    > On Tue, 25 Feb 2014 21:27:07 +0530, Hemant Kumar wrote:
    >> On 02/25/2014 05:14 PM, Masami Hiramatsu wrote:
    >>> (2014/02/24 18:14), Hemant Kumar wrote:
    >>>> First, scan the binaries using :
    >>>> # perf list sdt --scan
    >>>>
    >>>> Creating a cache of SDT markers...
    >>>> perf sdt cache created!
    >>>> Use : "perf list sdt"
    >>>> to see the SDT markers
    >>> Hmm, in that case, I think you'd better introduce perf-sdt for scanning.
    >>> e.g.
    >>>
    >>> # perf sdt --scan app
    >> Hmm, this seems a better idea :)
    >>
    >>> then you can add app to sdt cache, without app,
    >>>
    >>> # perf sdt --scan
    >>>
    >>> will just scans all binaries on the PATH and the libraries which listed
    >>> by `ldconfig --print-caceh`
    > What should be done with the new perf sdt command? If it's only
    > intended to list the markers, I'd just suggest to add "perf list sdt" as
    > this patch did.

    If we display the SDT markers along with the other events in perf list,
    then I think we can go with
    perf list sdt. I am not too sure though! :)

    For me, the main issue was that the markers are not events. They become
    events after
    we place them in the uprobe_events file just like functions. But we use
    `perf list` to
    display all the "events" available on a system. Isn't it?

    > Plus I think it'd be better if event_glob pattern also looks for sdt
    > markers so that user can find out a specific markers easily, e.g.:
    >
    > # perf list rtld:*
    >
    > or
    >
    > # perf list %rtld:*

    Good idea! Will surely include support for this in event_glob pattern.

    >>> And perf-list shows only the SDTs in the cache.
    >> Well, what will be better? perf-list or perf-sdt or perf-list sdt??
    >> If perf-list, then wouldn't it be a huge list!!
    > The output of perf list is already a huge list and we paginate it. So I
    > don't think it's gonna be a problem. :)

    Ok! Then we can use perf list. :)

    >
    >>>> - Add support to probe these SDT markers and integrate with a previous patch
    >>>> (support to perf to probe SDT markers) posted in lkml.
    >>>> https://lkml.org/lkml/2013/10/23/10
    >>> Yeah, but I think we'd better choose another way to integrate it.
    >>> Since SDT is like markers(static events), setting each of them via perf-probe is
    >>> not intuitive. :) I'd like to use it as an event, e.g.
    >>>
    >>> # perf top -e "%libgcc:unwind"
    >>>
    >>> And perf top internally calls perf-probe to add new uprobe event, and
    >>> clean the new event at exit.
    >> Yeah! Right :) Makes sense.
    >>
    >> Will implement the suggestions in the next version asap!
    > That would be great!

    --
    Thanks
    Hemant Kumar



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