From: Adrian Hunter <[email protected]>

The 'idx' member was added as preparation for AUX area sampling. Add a
comment to describe why.

Signed-off-by: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Michael Petlan <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/util/evsel.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 9cd6e3ae479a..efe08065838f 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -23,6 +23,13 @@ struct perf_sample_id {
        struct hlist_node       node;
        u64                     id;
        struct evsel            *evsel;
+       /*
+       * 'idx' will be used for AUX area sampling. A sample will have AUX area
+       * data that will be queued for decoding, where there are separate
+       * queues for each CPU (per-cpu tracing) or task (per-thread tracing).
+       * The sample ID can be used to lookup 'idx' which is effectively the
+       * queue number.
+       */
        int                     idx;
        int                     cpu;
        pid_t                   tid;
-- 
2.21.0

Reply via email to