On 12/05/2021 17:39, James Clark wrote:

On 29/04/2021 18:00, Leo Yan wrote:

quoted

The dummy event is mainly used for mmap, the TIME sample is only needed

[...]

quoted

-	tracking_evsel->core.attr.freq = 0;
-	tracking_evsel->core.attr.sample_period = 1;
-	evsel__set_sample_bit(tracking_evsel, TIME);
-	evsel__set_sample_bit(tracking_evsel, CPU);
-	evsel__reset_sample_bit(tracking_evsel, BRANCH_STACK);
+	if (opts->full_auxtrace) {
+		struct evsel *tracking_evsel;

Hi Leo,

I know the "if (opts->full_auxtrace)" pattern is copied from other auxtrace
files, but I don't think it does anything because there is this at the top
of the function:

   	if (!opts->full_auxtrace)
		return 0;

The same applies for other usages of "full_auxtrace" in the same function.
They are all always true. I'm also not sure if it's ever defined what
full_auxtrace means.

James

Apart from this issue above, I've tested the full patchset with various combinations
of --per-thread, -a and --timestamp and don't see any issues like missing command names
or decode issues. (Apart from -a where Command is reported as '-1', but this issue is
present before and after this patchset so is unrelated.)

I think it makes sense to unify the behaviour to make it more like Coresight and others
so this is a good change.

Reviewed-by: James Clark <redacted>
Tested-by: James Clark <redacted>

quoted

+
+		err = parse_events(evlist, "dummy:u", NULL);
+		if (err)
+			return err;
+
+		tracking_evsel = evlist__last(evlist);
+		evlist__set_tracking_event(evlist, tracking_evsel);
+
+		tracking_evsel->core.attr.freq = 0;
+		tracking_evsel->core.attr.sample_period = 1;
+
+		/* In per-cpu case, always need the time of mmap events etc */
+		if (!perf_cpu_map__empty(cpus))
+			evsel__set_sample_bit(tracking_evsel, TIME);
+	}
 
 	return 0;
 }

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