The hierarchy output mode is to group entries for each level so that
user can see higher level picture more easily.  It also helps to find
out which component is most costly.  The output will look like below:

      15.11%     swapper
         14.97%     [kernel.vmlinux]
          0.09%     [libahci]
          0.05%     [iwlwifi]
      10.29%     irq/33-iwlwifi
          6.45%     [kernel.vmlinux]
          1.41%     [mac80211]
          1.15%     [iwldvm]
          1.14%     [iwlwifi]
          0.14%     [cfg80211]
       4.81%     firefox
          3.92%     libxul.so
          0.34%     [kernel.vmlinux]
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Acked-by: NPekka Enberg <penberg@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1456326830-30456-10-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>