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SubjectRe: [PATCH v3 6/8] perf session: Move event read code to separate function
On Mon, Oct 11, 2021 at 12:53:30PM +0300, Bayduraev, Alexey V wrote:
>
>
> On 11.10.2021 12:08, Bayduraev, Alexey V wrote:
> >
> > On 08.10.2021 17:38, Jiri Olsa wrote:
> >> On Fri, Oct 08, 2021 at 11:42:18AM +0300, Bayduraev, Alexey V wrote:
> >>>
> >>>
> >>> On 08.10.2021 10:33, Jiri Olsa wrote:
> >>>> On Thu, Oct 07, 2021 at 01:25:41PM +0300, Alexey Bayduraev wrote:
> >>>>
> >>>> SNIP
> >>>>
> >>>>> static int
> >>>>> -reader__process_events(struct reader *rd, struct perf_session *session,
> >>>>> - struct ui_progress *prog)
> >>>>> +reader__read_event(struct reader *rd, struct perf_session *session,
> >>>>> + struct ui_progress *prog)
> >
> > SNIP
> >
> >>>>
> >>>> active_decomp should be set/unset within reader__process_events,
> >>>> not just for single event read, right?
> >>>
> >>> No, it should be set before perf_session__process_event/process_decomp_events
> >>> and unset after these calls. So active_decomp setting/unsetting is moved in
> >>> this patch to the reader__read_event function. This is necessary for multiple
> >>> trace reader because it could call reader__read_event in round-robin manner.
> >>
> >> hum, is that code already in? I can't see this happening in current code
> >
> > Probably I don't understand the question. In [PATCH v3 2/8] I introduced
> > active_decomp pointer in perf_session. It is initialized by a pointer to the
> > decompressor object in perf_session. In reader__process_events it is set to
> > the reader decompressor object. And it is reset to the session decompressor
> > object at exit. In this case we do not need to reset it after each
> > perf_session__process_event because this code reads events in loop with
> > constant reader object. Maybe setting of active_decomp should be at the
> > entrance to the reader__process_events, not before reader__process_events,
> > in [PATCH v3 2/8]. All this code is new.
>
> We set active_decomp for perf_session__process_event (rd->process() in our
> case) and for __perf_session__process_decomp_events, active_decomp is not
> necessary for other parts of reader__process_events.

so what I see in the code is:

__perf_session__process_events
{
struct reader rd;

reader__process_events(rd)
{
reader__read_event(rd)
{
-> session->active_decomp = &rd->decomp_data;
rd->process(...
-> session->active_decomp = &session->decomp_data;
}

}
}


we set session->active_decomp for each event that we process
and I don't understand why we can't do that just once in
__perf_session__process_events, so it'd be like:

__perf_session__process_events
{
struct reader rd;

-> session->active_decomp = &rd->decomp_data;

reader__process_events(rd)
{
reader__read_event(rd)
{
rd->process(...
}

}

-> session->active_decomp = &session->decomp_data;
}


or within reader__process_events if it's more convenient

jirka

>
> Regards,
> Alexey
>
> >
> > In this patch I separates single event reading and moves setting/resetting
> > of active_decomp before/after perf_session__process_event because this is
> > necessary for multiple trace reader.
> >
> > Regards,
> > Alexey
> >
> >>
> >> jirka
> >>
> >>>
> >>> Regards,
> >>> Alexey
> >>>
> >>>>
> >>>> jirka
> >>>>
> >>>>> return err;
> >>>>> }
> >>>>>
> >>>>> --
> >>>>> 2.19.0
> >>>>>
> >>>>
> >>>
> >>
>

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