[PATCH v2 3/7] perf record: Move setting dummy tracking before record__init_thread_masks()

[Yang Jihong]

When dummy tracking go system wide, the mmap cpu mask is changed.
Therefore, needs to be placed before record__init_thread_masks().
Dummy tracking has been set in record__open(), move it before
record__init_thread_masks() and add a helper for unified processing.

The sys_perf_event_open invoked is as follows:

  # perf --debug verbose=3 record -e cpu-clock -D 100 true
    <SNIP>
    Opening: cpu-clock
    ------------------------------------------------------------
    perf_event_attr:
      type                             1
      size                             136
      { sample_period, sample_freq }   4000
      sample_type                      IP|TID|TIME|PERIOD|IDENTIFIER
      read_format                      ID|LOST
      disabled                         1
      inherit                          1
      freq                             1
      sample_id_all                    1
      exclude_guest                    1
    ------------------------------------------------------------
    sys_perf_event_open: pid 6867  cpu 0  group_fd -1  flags 0x8 = 5
    sys_perf_event_open: pid 6867  cpu 1  group_fd -1  flags 0x8 = 6
    sys_perf_event_open: pid 6867  cpu 2  group_fd -1  flags 0x8 = 7
    sys_perf_event_open: pid 6867  cpu 3  group_fd -1  flags 0x8 = 9
    sys_perf_event_open: pid 6867  cpu 4  group_fd -1  flags 0x8 = 10
    sys_perf_event_open: pid 6867  cpu 5  group_fd -1  flags 0x8 = 11
    sys_perf_event_open: pid 6867  cpu 6  group_fd -1  flags 0x8 = 12
    sys_perf_event_open: pid 6867  cpu 7  group_fd -1  flags 0x8 = 13
    Opening: dummy:u
    ------------------------------------------------------------
    perf_event_attr:
      type                             1
      size                             136
      config                           0x9
      { sample_period, sample_freq }   1
      sample_type                      IP|TID|TIME|IDENTIFIER
      read_format                      ID|LOST
      disabled                         1
      inherit                          1
      exclude_kernel                   1
      exclude_hv                       1
      mmap                             1
      comm                             1
      enable_on_exec                   1
      task                             1
      sample_id_all                    1
      exclude_guest                    1
      mmap2                            1
      comm_exec                        1
      ksymbol                          1
      bpf_event                        1
    ------------------------------------------------------------
    sys_perf_event_open: pid 6867  cpu 0  group_fd -1  flags 0x8 = 14
    sys_perf_event_open: pid 6867  cpu 1  group_fd -1  flags 0x8 = 15
    sys_perf_event_open: pid 6867  cpu 2  group_fd -1  flags 0x8 = 16
    sys_perf_event_open: pid 6867  cpu 3  group_fd -1  flags 0x8 = 17
    sys_perf_event_open: pid 6867  cpu 4  group_fd -1  flags 0x8 = 18
    sys_perf_event_open: pid 6867  cpu 5  group_fd -1  flags 0x8 = 19
    sys_perf_event_open: pid 6867  cpu 6  group_fd -1  flags 0x8 = 20
    sys_perf_event_open: pid 6867  cpu 7  group_fd -1  flags 0x8 = 21
    <SNIP>

Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx>
---
 tools/perf/builtin-record.c | 59 +++++++++++++++++++++++--------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index ca83599cc50c..ccbcb005e188 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -908,6 +908,37 @@ 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;
+
+	/*
+	 * For initial_delay, system wide or a hybrid system, we need to add a
+	 * dummy event so that we can track PERF_RECORD_MMAP to cover the delay
+	 * of waiting or event synthesis.
+	 */
+	if (opts->target.initial_delay || target__has_cpu(&opts->target) ||
+	    perf_pmus__num_core_pmus() > 1) {
+		evsel = evlist__findnew_tracking_event(evlist, false);
+		if (!evsel)
+			return -ENOMEM;
+
+		/*
+		 * Enable the dummy event when the process is forked for
+		 * initial_delay, immediately for system wide.
+		 */
+		if (opts->target.initial_delay && !evsel->immediate &&
+		    !target__has_cpu(&opts->target))
+			evsel->core.attr.enable_on_exec = 1;
+		else
+			evsel->immediate = 1;
+	}
+
+	return 0;
+}
+
 static bool record__kcore_readable(struct machine *machine)
 {
 	char kcore[PATH_MAX];
@@ -1288,28 +1319,6 @@ static int record__open(struct record *rec)
 	struct record_opts *opts = &rec->opts;
 	int rc = 0;
 
-	/*
-	 * For initial_delay, system wide or a hybrid system, we need to add a
-	 * dummy event so that we can track PERF_RECORD_MMAP to cover the delay
-	 * of waiting or event synthesis.
-	 */
-	if (opts->target.initial_delay || target__has_cpu(&opts->target) ||
-	    perf_pmus__num_core_pmus() > 1) {
-		pos = evlist__findnew_tracking_event(evlist, false);
-		if (!pos)
-			return -ENOMEM;
-
-		/*
-		 * Enable the dummy event when the process is forked for
-		 * initial_delay, immediately for system wide.
-		 */
-		if (opts->target.initial_delay && !pos->immediate &&
-		    !target__has_cpu(&opts->target))
-			pos->core.attr.enable_on_exec = 1;
-		else
-			pos->immediate = 1;
-	}
-
 	evlist__config(evlist, opts, &callchain_param);
 
 	evlist__for_each_entry(evlist, pos) {
@@ -4235,6 +4244,12 @@ 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