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    SubjectRe: [PATCH v4 2/3] Support for perf to probe into SDT markers:
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    Hi Ingo,

    On Sat, 26 Oct 2013 11:50:23 +0200, Ingo Molnar wrote:
    > * Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:
    >
    >> Hi Pekka,
    >>
    >> > >
    >> > > You can now use it in all perf tools, such as:
    >> > >
    >> > > perf record -e libc:my_event -aR sleep 1
    >> >
    >> > Is there a technical reason why 'perf list' could not show all the
    >> > available SDT markers on a system and that the 'market to event'
    >> > mapping cannot happen automatically?
    >> >
    >>
    >> Technically feasible. But then we would have to parse each of the
    >> libraries and executables to list them. Right? I am not sure if
    >> such a delay is acceptable.
    >
    > I'd say lets try Pekka's suggestion and make it more palatable if
    > there's complaints about the delay. (SSD systems are becoming
    > dominant and there the search should be reasonably fast.)
    >
    > We could also make 'perf list' more sophisticated, if invoked
    > naively as 'perf list' then maybe it should first display the
    > various event categories, with a (rough) count:
    >
    > $ perf list
    > 34 hardware events # use 'perf list --hw' to list them
    > 40 hw-cache events # use 'perf list --cache' to list them
    > 20 software events # use 'perf list --sw' to list them
    > 2 raw events # use 'perf list --raw' to list them
    > 120 tracepoints # use 'perf list --tp' to list them
    > >10 SDT tracepoints # use 'perf list --sdt' to list them
    >
    > # use 'perf list -a' to list all events
    > # use 'perf list ./binary' to list events in a given binary
    >
    > I.e. bring a bit more structure into it.

    I like this. :)

    Note that 'perf list' already support this kind of filtering now:

    $ perf list hw cache sw tracepoint pmu

    or

    $ perf list sched:*

    It'd be great if this globbing also supports SDTs.

    And for 'perf list ./binary' case, it could detect libraries in the
    dependency list and then also scan them.

    >
    >> Also if a binary exists in a path thats is not covered in the
    >> default search, an user might believe that his binary may not have
    >> markers. I know the above reason is more of a user folly than a
    >> tooling issue.
    >
    > I think in 99% of the usecases people will either use pre-built
    > markers that come with their distro, or will be intimately aware of
    > the markers because they are in the very app they are developing.
    >
    > So I wouldn't worry about 'user has a weird binary' case too much.
    >
    > I agree with Pekka that making them easily discoverable and visible
    > as a coherent whole is really important.

    Agreed. We do need to improve the user experience of the perf tools!

    Thanks,
    Namhyung


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