perf evsel: Add comment for 'idx' member in 'struct perf_sample_id

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

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/83ff264f-84c3-5372-8976-dd9293d20c6f@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2019-08-12 12:09:35 +03:00 committed by Arnaldo Carvalho de Melo
parent 0ac10d87a5
commit 3c84e65a53
1 changed files with 7 additions and 0 deletions

View File

@ -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;