[PATCH] perf top: Display the LBR stats in callchain entry

[Jin Yao]

Perf report has supported the displaying of LBR stats
(such as cycles, predicted%) in callchain entry.

For example,
perf report --branch-history --stdio

--1.01%--intel_idle mwait.h:29
          intel_idle cpufeature.h:164 (cycles:5)
          intel_idle cpufeature.h:164 (predicted:76.4%)
          intel_idle mwait.h:102 (cycles:41)
          intel_idle current.h:15

While perf top has not supported that.

For example,
perf top -a -b --call-graph branch

-   13.86%     0.23%  [kernel]		[k] __x86_indirect_thunk_rax
   - 13.65% __x86_indirect_thunk_rax
      + 1.69% do_syscall_64
      + 1.68% do_select
      + 1.41% ktime_get
      + 0.70% __schedule
      + 0.62% do_sys_poll
        0.58% __x86_indirect_thunk_rax

Actually it's very easy to enable this feature in perf top.

With this patch, the result is:

perf top -a -b --call-graph branch

-   13.58%     0.00%  [kernel]		[k] __x86_indirect_thunk_rax
   - 13.57% __x86_indirect_thunk_rax (predicted:93.9%)
      + 1.78% do_select (cycles:2)
      + 1.68% perf_pmu_disable.part.99 (cycles:1)
      + 1.45% ___sys_recvmsg (cycles:25)
      + 0.81% unix_stream_sendmsg (cycles:18)
      + 0.80% ktime_get (cycles:400)
        0.58% pick_next_task_fair (cycles:47)
      + 0.56% i915_request_retire (cycles:2)
      + 0.52% do_sys_poll (cycles:4)

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
 tools/perf/builtin-top.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d21d875..7691b21 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1420,6 +1420,9 @@ int cmd_top(int argc, const char **argv)
 		}
 	}
 
+	if (opts->branch_stack && callchain_param.enabled)
+		symbol_conf.show_branchflag_count = true;
+
 	sort__mode = SORT_MODE__TOP;
 	/* display thread wants entries to be collapsed in a different tree */
 	perf_hpp_list.need_collapse = 1;
-- 
2.7.4