Messages in this thread Patch in this message | | | From | Yang Jihong <> | Subject | [PATCH 3/5] perf record: Tracking side-band events for all CPUs when tracing selected CPUs | Date | Tue, 4 Jul 2023 07:42:15 +0000 |
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User space tasks can migrate between CPUs, we need to track side-band events for all CPUs.
The specific scenarios are as follows:
CPU0 CPU1 perf record -C 0 start taskA starts to be created and executed -> PERF_RECORD_COMM and PERF_RECORD_MMAP events only deliver to CPU1 ...... | migrate to CPU0 | Running on CPU0 <----------/ ...
perf record -C 0 stop
Now perf samples the PC of taskA. However, perf does not record the PERF_RECORD_COMM and PERF_RECORD_COMM events of taskA. Therefore, the comm and symbols of taskA cannot be parsed.
The sys_perf_event_open invoked is as follows:
# perf --debug verbose=3 record -e cpu-clock -C 1 true <SNIP> Opening: cpu-clock ------------------------------------------------------------ perf_event_attr: type 1 size 136 { sample_period, sample_freq } 4000 sample_type IP|TID|TIME|ID|CPU|PERIOD read_format ID|LOST disabled 1 inherit 1 freq 1 sample_id_all 1 exclude_guest 1 ------------------------------------------------------------ sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 5 Opening: dummy:HG ------------------------------------------------------------ perf_event_attr: type 1 size 136 config 0x9 { sample_period, sample_freq } 4000 sample_type IP|TID|TIME|ID|CPU|PERIOD read_format ID|LOST inherit 1 mmap 1 comm 1 freq 1 task 1 sample_id_all 1 mmap2 1 comm_exec 1 ksymbol 1 bpf_event 1 ------------------------------------------------------------ sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 6 sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 7 sys_perf_event_open: pid -1 cpu 2 group_fd -1 flags 0x8 = 9 sys_perf_event_open: pid -1 cpu 3 group_fd -1 flags 0x8 = 10 sys_perf_event_open: pid -1 cpu 4 group_fd -1 flags 0x8 = 11 sys_perf_event_open: pid -1 cpu 5 group_fd -1 flags 0x8 = 12 sys_perf_event_open: pid -1 cpu 6 group_fd -1 flags 0x8 = 13 sys_perf_event_open: pid -1 cpu 7 group_fd -1 flags 0x8 = 14 <SNIP>
Signed-off-by: Yang Jihong <yangjihong1@huawei.com> --- tools/perf/builtin-record.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 8872cd037f2c..69e0d8c75aab 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -908,6 +908,31 @@ static int record__config_off_cpu(struct record *rec) return off_cpu_prepare(rec->evlist, &rec->opts.target, &rec->opts); } +static int record__config_tracking_events(struct record *rec) +{ + struct evsel *evsel; + struct evlist *evlist = rec->evlist; + struct record_opts *opts = &rec->opts; + + /* + * User space tasks can migrate between CPUs, so when tracing + * selected CPUs, sideband for all CPUs is still needed. + */ + if (opts->target.cpu_list) { + evsel = evlist__findnew_tracking_event(evlist); + if (!evsel) + return -ENOMEM; + + if (!evsel->core.system_wide) { + evsel->core.system_wide = true; + evsel__set_sample_bit(evsel, TIME); + perf_evlist__propagate_maps(&evlist->core, &evsel->core); + } + } + + return 0; +} + static bool record__kcore_readable(struct machine *machine) { char kcore[PATH_MAX]; @@ -4235,6 +4260,12 @@ int cmd_record(int argc, const char **argv) goto out; } + err = record__config_tracking_events(rec); + if (err) { + pr_err("record__config_tracking_events failed, error %d\n", err); + goto out; + } + err = record__init_thread_masks(rec); if (err) { pr_err("Failed to initialize parallel data streaming masks\n"); -- 2.30.GIT
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