From: Jiri Olsa <jolsa@redhat.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Clark Williams <williams@redhat.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Song Liu <songliubraving@fb.com>, Wang Nan <wangnan0@huawei.com>
Subject: Re: [PATCH 7/7] perf record: Introduce --switch-output-event
Date: Tue, 28 Apr 2020 15:22:57 +0200 [thread overview]
Message-ID: <20200428132257.GH1476763@krava> (raw)
In-Reply-To: <20200428121601.GB2245@kernel.org>
On Tue, Apr 28, 2020 at 09:16:01AM -0300, Arnaldo Carvalho de Melo wrote:
SNIP
> > > + pr_err("Couldn't create side band evlist.\n.");
> > > + goto out_child;
> > > + }
> > > }
> > >
> > > if (evlist__add_bpf_sb_event(rec->sb_evlist, &session->header.env)) {
> >
> > it's getting bigger, I wonder we should put all the sb_* setup in
> > separated functions like sb_start/sb_stop
>
> Well, the rec->thread_id = pthread_self(); part is just for reusing a
> 'perf record' specific mechanism, what to do when the event appears in
> the side band thread ring buffer, the evlist__set_cb() also is related
> to that, moving thread_id to evlist seems too much at this time.
hum, I meant record specific static functions sb_start/sb_stop,
not inside evlist.. just to have it separated
>
> > > @@ -2179,10 +2199,19 @@ static int switch_output_setup(struct record *rec)
> > > };
> > > unsigned long val;
> > >
> > > + /*
> > > + * If we're using --switch-output-events, then we imply its
> > > + * --switch-output=signal, as we'll send a SIGUSR2 from the side band
> > > + * thread to its parent.
> > > + */
> > > + if (rec->sb_evlist != NULL)
> > > + goto do_signal;
> > > +
> > > if (!s->set)
> > > return 0;
>
> > hum, it looks like this jump is not necessay and can be avoided
> > by some bool checks.. could we add some bool when --switch-output-event
> > is used, so we don't depend on wether rec->sb_evlist was allocated for
> > whatever reason?
>
> If rec->sb_evlist is NULL, then there was no --switch-output-event
> passed... The only advantage in adding the complexity below would be if
> we had rec->switch_output_event_set which would clarify that sb_evlist
> is not used only for --switch-output-event, to make things clearer.
>
> And this still leaves us with the jump, otherwise we would have to test
> it twice, right?
still I like the idea of checking bool twice then adding jumps
>
> I think I'll separate the patch adding OPT_CALLBACK_SET(), then fold the
> switch_output_event_set addition to builtin-record, ok?
ok, or set the bool directly in the callback, both works for me ;-)
thanks,
jirka
next prev parent reply other threads:[~2020-04-28 13:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 21:19 [RFC PATCHSET] Implement --switch-output-events Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 1/7] perf record: Move sb_evlist to 'struct record' Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 2/7] perf top: Move sb_evlist to 'struct perf_top' Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 3/7] perf bpf: Decouple creating the evlist from adding the SB event Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 4/7] " Arnaldo Carvalho de Melo
2020-04-28 9:48 ` Jiri Olsa
2020-04-28 17:21 ` Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 5/7] perf parse-events: Add parse_events_option() variant that creates evlist Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 6/7] perf evlist: Allow reusing the side band thread for more purposes Arnaldo Carvalho de Melo
2020-04-27 21:19 ` [PATCH 7/7] perf record: Introduce --switch-output-event Arnaldo Carvalho de Melo
2020-04-28 9:48 ` Jiri Olsa
2020-04-28 12:16 ` Arnaldo Carvalho de Melo
2020-04-28 13:22 ` Jiri Olsa [this message]
2020-04-28 18:05 ` Arnaldo Carvalho de Melo
2020-04-29 8:18 ` Jiri Olsa
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