From 899e5ffbf246a30986ced9dd48092c408978afc7 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 27 Apr 2020 17:56:37 -0300 Subject: [PATCH] perf record: Introduce --switch-output-event Now we can use it with --overwrite to have a flight recorder mode that gets snapshot requests from arbitrary events that are processed in the side band thread together with the PERF_RECORD_BPF_EVENT processing. Example: To collect scheduler events until a recvmmsg syscall happens, system wide: [root@five a]# rm -f perf.data.2020042717* [root@five a]# perf record --overwrite -e sched:*switch,syscalls:*recvmmsg --switch-output-event syscalls:sys_enter_recvmmsg [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042717585458 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042717590235 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042717590398 ] ^C[ perf record: Woken up 1 times to write data ] [ perf record: Dump perf.data.2020042717590511 ] [ perf record: Captured and wrote 7.244 MB perf.data. ] So in the above case we had 3 snapshots, the fourth was forced by control+C: [root@five a]# ls -la total 20440 drwxr-xr-x. 2 root root 4096 Apr 27 17:59 . dr-xr-x---. 12 root root 4096 Apr 27 17:46 .. -rw-------. 1 root root 3936125 Apr 27 17:58 perf.data.2020042717585458 -rw-------. 1 root root 5074869 Apr 27 17:59 perf.data.2020042717590235 -rw-------. 1 root root 4291037 Apr 27 17:59 perf.data.2020042717590398 -rw-------. 1 root root 7617037 Apr 27 17:59 perf.data.2020042717590511 [root@five a]# One can make this more precise by adding the switch output event to the main -e events list, as since this is done asynchronously, a few events after the signal event will appear in the snapshots, as can be seen with: [root@five a]# rm -f perf.data.20200427175* [root@five a]# perf record --overwrite -e sched:*switch,syscalls:*recvmmsg --switch-output-event syscalls:sys_enter_recvmmsg [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042718024203 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042718024301 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2020042718024484 ] ^C[ perf record: Woken up 1 times to write data ] [ perf record: Dump perf.data.2020042718024562 ] [ perf record: Captured and wrote 7.337 MB perf.data. ] [root@five a]# perf script -i perf.data.2020042718024203 | tail -15 PacerThread 148586 [005] 122.830729: sched:sched_switch: prev_comm=PacerThread prev_pid=148586... swapper 0 [000] 122.833588: sched:sched_switch: prev_comm=swapper/0 prev_pid=... NetworkManager 1251 [000] 122.833619: syscalls:sys_enter_recvmmsg: fd: 0x0000001c, mmsg: 0x7ffe83054a1... swapper 0 [002] 122.833624: sched:sched_switch: prev_comm=swapper/2 prev_pid=... swapper 0 [003] 122.833624: sched:sched_switch: prev_comm=swapper/3 prev_pid=... NetworkManager 1251 [000] 122.833626: syscalls:sys_exit_recvmmsg: 0x1 kworker/3:3-eve 158946 [003] 122.833628: sched:sched_switch: prev_comm=kworker/3:3 prev_pid=15894... swapper 0 [004] 122.833641: sched:sched_switch: prev_comm=swapper/4 prev_pid=... NetworkManager 1251 [000] 122.833642: sched:sched_switch: prev_comm=NetworkManage... perf 228273 [002] 122.833645: sched:sched_switch: prev_comm=perf prev_pid=22827... swapper 0 [011] 122.833646: sched:sched_switch: prev_comm=swapper/1... swapper 0 [002] 122.833648: sched:sched_switch: prev_comm=swapper/... kworker/0:2-eve 207387 [000] 122.833648: sched:sched_switch: prev_comm=kworker/0:2 prev_pid=20738... kworker/2:3-eve 232038 [002] 122.833652: sched:sched_switch: prev_comm=kworker/2:3 prev_pid=23203... perf 235825 [003] 122.833653: sched:sched_switch: prev_comm=perf prev_pid=23582... [root@five a]# Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Namhyung Kim Cc: Song Liu Cc: Wang Nan Link: http://lore.kernel.org/lkml/20200429131106.27974-8-acme@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-record.txt | 13 ++++++++ tools/perf/builtin-record.c | 41 +++++++++++++++++++++--- 2 files changed, 50 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. + --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 5b6a1d23efe5..bb5b4d2fc32b 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -88,7 +88,9 @@ struct record { struct evlist *evlist; struct perf_session *session; struct evlist *sb_evlist; + pthread_t thread_id; int realtime_prio; + bool switch_output_event_set; bool no_buildid; bool no_buildid_set; bool no_buildid_cache; @@ -1437,6 +1439,13 @@ 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; @@ -1581,12 +1590,24 @@ 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)) { @@ -2180,10 +2201,19 @@ 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->switch_output_event_set) + goto do_signal; + if (!s->set) return 0; if (!strcmp(s->str, "signal")) { +do_signal: s->signal = true; pr_debug("switch-output with SIGUSR2 signal\n"); goto enabled; @@ -2441,6 +2471,9 @@ 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_SET(0, "switch-output-event", &record.sb_evlist, &record.switch_output_event_set, "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,