'perf report' supports the option --group-sort-idx, which sorts the
output by the event at the index n in event group.
For example:
  perf record -e cycles,instructions,cache-misses
  perf report --group --group-sort-idx 2 --stdio
The perf-report output is sorted by cache-misses.
This patch supports --group-sort-idx in perf-top.
For example:
  perf top --group -e cycles,instructions,cache-misses --group-sort-idx 2
The perf-top output is sorted by cache-misses.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200324220711.6025-1-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 --group::
         Put the counters into a counter group.
 
+--group-sort-idx::
+       Sort the output by the event at the index n in group. If n is invalid,
+       sort by the first event. It can support multiple groups with different
+       amount of events. WARNING: This should be used on grouped events.
+
 -F <freq>::
 --freq=<freq>::
        Profile at this frequency. Use 'max' to use the currently maximum
 
                    "Record namespaces events"),
        OPT_BOOLEAN(0, "all-cgroups", &opts->record_cgroup,
                    "Record cgroup events"),
+       OPT_INTEGER(0, "group-sort-idx", &symbol_conf.group_sort_idx,
+                   "Sort the output by the event at the index n in group. "
+                   "If n is invalid, sort by the first event. "
+                   "WARNING: should be used on grouped events."),
        OPTS_EVSWITCH(&top.evswitch),
        OPT_END()
        };