Re: [PATCH 7/7] perf record: Introduce --switch-output-event

From: Arnaldo Carvalho de Melo
Date: Tue Apr 28 2020 - 14:05:26 EST


Em Tue, Apr 28, 2020 at 03:22:57PM +0200, Jiri Olsa escreveu:
> 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

Ok, so I have the patch below on top of that series, and its all
available in my perf/switch-output-event, that is on top of more patches
collected today, all going well, this perf/switch-output-event will turn
into perf/core ang go upstream soon, then I have to loo at Adrian's
kernel+tooling patchkit,

- Arnaldo

commit a25516b4db23ba8f956b990d37ec6728e5221718
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date: Tue Apr 28 14:58:29 2020 -0300

perf record: Move side band evlist setup to separate routine

It is quite big by now, move that code to a separate
record__setup_sb_evlist() routine.

Suggested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7a6a89972691..bb3d30616bf3 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1445,6 +1445,44 @@ static int record__process_signal_event(union perf_event *event __maybe_unused,
return 0;
}

+static int record__setup_sb_evlist(struct record *rec)
+{
+ struct record_opts *opts = &rec->opts;
+
+ if (rec->sb_evlist != NULL) {
+ /*
+ * We get here if --switch-output-event populated the
+ * sb_evlist, so associate a callback that will send a SIGUSR2
+ * to the main thread.
+ */
+ evlist__set_cb(rec->sb_evlist, record__process_signal_event, rec);
+ rec->thread_id = pthread_self();
+ }
+
+ if (!opts->no_bpf_event) {
+ if (rec->sb_evlist == NULL) {
+ rec->sb_evlist = evlist__new();
+
+ if (rec->sb_evlist == NULL) {
+ pr_err("Couldn't create side band evlist.\n.");
+ return -1;
+ }
+ }
+
+ if (evlist__add_bpf_sb_event(rec->sb_evlist, &rec->session->header.env)) {
+ pr_err("Couldn't ask for PERF_RECORD_BPF_EVENT side band events.\n.");
+ return -1;
+ }
+ }
+
+ if (perf_evlist__start_sb_thread(rec->sb_evlist, &rec->opts.target)) {
+ pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
+ opts->no_bpf_event = true;
+ }
+
+ return 0;
+}
+
static int __cmd_record(struct record *rec, int argc, const char **argv)
{
int err;
@@ -1589,36 +1627,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
goto out_child;
}

- if (rec->sb_evlist != NULL) {
- /*
- * We get here if --switch-output-event populated the
- * sb_evlist, so associate a callback that will send a SIGUSR2
- * to the main thread.
- */
- evlist__set_cb(rec->sb_evlist, record__process_signal_event, rec);
- rec->thread_id = pthread_self();
- }
-
- if (!opts->no_bpf_event) {
- if (rec->sb_evlist == NULL) {
- rec->sb_evlist = evlist__new();
-
- if (rec->sb_evlist == NULL) {
- pr_err("Couldn't create side band evlist.\n.");
- goto out_child;
- }
- }
-
- if (evlist__add_bpf_sb_event(rec->sb_evlist, &session->header.env)) {
- pr_err("Couldn't ask for PERF_RECORD_BPF_EVENT side band events.\n.");
- goto out_child;
- }
- }
-
- if (perf_evlist__start_sb_thread(rec->sb_evlist, &rec->opts.target)) {
- pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
- opts->no_bpf_event = true;
- }
+ err = record__setup_sb_evlist(rec);
+ if (err)
+ goto out_child;

err = record__synthesize(rec, false);
if (err < 0)