Messages in this thread | | | Date | Tue, 28 Apr 2020 11:48:39 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 7/7] perf record: Introduce --switch-output-event |
| |
On Mon, Apr 27, 2020 at 06:19:35PM -0300, Arnaldo Carvalho de Melo wrote:
SNIP
> --- > tools/perf/Documentation/perf-record.txt | 13 ++++++++ > tools/perf/builtin-record.c | 40 +++++++++++++++++++++--- > 2 files changed, 49 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt > index 6e8b4649307c..561ef55743e2 100644 > --- a/tools/perf/Documentation/perf-record.txt > +++ b/tools/perf/Documentation/perf-record.txt > @@ -556,6 +556,19 @@ overhead. You can still switch them on with: > > --switch-output --no-no-buildid --no-no-buildid-cache > > +--switch-output-event:: > +Events that will cause the switch of the perf.data file, auto-selecting > +--switch-output=signal, the results are similar as internally the side band > +thread will also send a SIGUSR2 to the main one. > + > +Uses the same syntax as --event, it will just not be recorded, serving only to > +switch the perf.data file as soon as the --switch-output event is processed by > +a separate sideband thread. > + > +This sideband thread is also used to other purposes, like processing the > +PERF_RECORD_BPF_EVENT records as they happen, asking the kernel for extra BPF > +information, etc.
first I thought we should follow the --switch-output 'xxx' way, but then you need to specify an event, so I guess --switch-output-event is better
> + > --switch-max-files=N:: > > When rotating perf.data with --switch-output, only keep N files. > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index ed2244847400..8ff5eaec26e9 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -87,6 +87,7 @@ struct record { > struct evlist *evlist; > struct perf_session *session; > struct evlist *sb_evlist; > + pthread_t thread_id; > int realtime_prio; > bool no_buildid; > bool no_buildid_set; > @@ -1436,6 +1437,13 @@ static int record__synthesize(struct record *rec, bool tail) > return err; > } > > +static int record__process_signal_event(union perf_event *event __maybe_unused, void *data) > +{ > + struct record *rec = data; > + pthread_kill(rec->thread_id, SIGUSR2); > + return 0; > +} > + > static int __cmd_record(struct record *rec, int argc, const char **argv) > { > int err; > @@ -1580,12 +1588,24 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) > goto out_child; > } > > - if (!opts->no_bpf_event) { > - rec->sb_evlist = evlist__new(); > + 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) { > - pr_err("Couldn't create side band evlist.\n."); > - goto out_child; > + 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)) {
it's getting bigger, I wonder we should put all the sb_* setup in separated functions like sb_start/sb_stop
> @@ -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?
jirka
> > if (!strcmp(s->str, "signal")) { > +do_signal: > s->signal = true; > pr_debug("switch-output with SIGUSR2 signal\n"); > goto enabled; > @@ -2440,6 +2469,9 @@ static struct option __record_options[] = { > &record.switch_output.set, "signal or size[BKMG] or time[smhd]", > "Switch output when receiving SIGUSR2 (signal) or cross a size or time threshold", > "signal"), > + OPT_CALLBACK(0, "switch-output-event", &record.sb_evlist, "switch output event", > + "switch output event selector. use 'perf list' to list available events", > + parse_events_option_new_evlist), > OPT_INTEGER(0, "switch-max-files", &record.switch_output.num_files, > "Limit number of switch output generated files"), > OPT_BOOLEAN(0, "dry-run", &dry_run, > -- > 2.21.1 >
| |