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Subject[PATCH 01/30] perf evlist: Set the correct idx when adding dummy events
From: Arnaldo Carvalho de Melo <>

The evsel->idx field is used mainly to access the right bucket in
per-event arrays such as the annotation ones, but also to set
evsel->tracking, that in turn will decide what of the events will ask
for PERF_RECORD_{MMAP,COMM,EXEC} to be generated, i.e. which
perf_event_attr will have its mmap, etc fields set.

When we were adding the "dummy" event using perf_evlist__add_dummy() we
were not setting it correctly, which could result in multiple tracking

Now that I'll try using a dummy event to be the tracking one when using
'perf record --delay', i.e. when we process the --delay
setting we may already have the evlist set up, like with:

perf record -e cycles,instructions --delay 1000 ./workload

We will need to add a "dummy" event, then reset evsel->tracking for the
first event, "cycles", and set it instead to the dummy one, and also
setting its attr.enable_on_exec, so that we get the PERF_RECORD_MMAP,
etc metadata events while waiting to enable the explicitely requested
events, so lets get this straight and set the right evsel->idx.

Cc: Adrian Hunter <>
Cc: Bram Stolk <>
Cc: David Ahern <>
Cc: Jiri Olsa <>
Cc: Namhyung Kim <>
Cc: Wang Nan <>
Signed-off-by: Arnaldo Carvalho de Melo <>
tools/perf/util/evlist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index c6c891e154a6..ccb749f9a83f 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -257,7 +257,7 @@ int perf_evlist__add_dummy(struct perf_evlist *evlist)
.size = sizeof(attr), /* to capture ABI version */
- struct perf_evsel *evsel = perf_evsel__new(&attr);
+ struct perf_evsel *evsel = perf_evsel__new_idx(&attr, evlist->nr_entries);

if (evsel == NULL)
return -ENOMEM;
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