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    SubjectRe: [PATCH] tracing/filters: add run-time field descriptions to TRACE_EVENT_FORMAT events

    * Tom Zanussi <> wrote:

    > > Oh, do you know why these unfiltered event are disappearing?
    > It's because of the way ring_buffer_discard() currently works -
    > the filtered events are still there in the ring buffer taking up
    > space; they just aren't visible in the output because the read
    > skips over them.
    > So if there's a high volume of events being recorded, any given
    > event can be quickly overwritten before it has a chance to be
    > read, or it may have been read and appeared in the output, but
    > between the time it was read and the next cat, could easily have
    > been overwritten, and therefore 'disappears' on the next cat.
    > It's really no different from the normal case where there is no
    > filtering in place - the same thing would happen but you wouldn't
    > notice whether a particular event was still there or not the next
    > time you cat'ed the file, because of the large volume of events
    > being displayed. It's just more apparent when most of the events
    > are discarded and invisible.
    > At least that's my theory based on my understanding of how the
    > ring-buffer works...

    Correct, and this needs to be fixed.


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