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    SubjectRe: [PATCH V3 0/6] event synthesization multithreading for perf record

    * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

    > Em Tue, Oct 24, 2017 at 02:59:44PM +0200, Ingo Molnar escreveu:
    > >
    > > * Jiri Olsa <jolsa@redhat.com> wrote:
    > >
    > > > I recently made some changes on threaded record, which are based
    > > > on Namhyungs time* API, which is needed to read/sort the data afterwards
    > > >
    > > > but I wasn't able to get any substantial and constant reduce of LOST events
    > > > and then I got sidetracked and did not finish, but it's in here:
    > >
    > > So, in the context of system-wide profiling, the way that would work best I think
    > > is the following:
    > >
    > > thread #0 binds itself to CPU#0 (via sched_setaffinity) and creates a per-CPU event on CPU#0
    > > thread #1 binds itself to CPU#1 (via sched_setaffinity) and creates a per-CPU event on CPU#1
    > > thread #2 binds itself to CPU#2 (via sched_setaffinity) and creates a per-CPU event on CPU#2
    >
    > Right, that is how I think it should be done as well, and those will
    > just dump on separate files, in a per session directory, with an extra
    > file for the session details, in what is now the header.

    Yes. Also note how easy to examine such a directory structure is - I'd suggest
    making all the session details textual eventually. I.e. only the ring-buffers
    should be binary, the rest should be arch-independent text encoding.

    It's also very extensible.

    > Later, the same thing happens at processing time, this time we'll have
    > contention to access global thread state, the need for rounds of
    > PERF_SAMPLE_TIME based ordering, like what we have now in the
    > tools/perf/util/ordered-events.[ch] code, etc.
    >
    > This works for both 'report', 'script', 'top', 'trace', etc, as is
    > basically the model we already have. All the work that was done for
    > refcounting the thread, map, etc as well as locking those rbtrees would
    > finally be taken full advantage of.

    Yeah, cool!

    Thanks,

    Ingo

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