[PATCH v2 14/14] perf c2c: document function view in perf-c2c man page

[Jiebin Sun <jiebin.sun@intel.com>]

Describe the three-level function-view hierarchy (primary function,
sharing functions, shared cachelines) and the TAB/ESC/d/e key
bindings that drive it.

Signed-off-by: Jiebin Sun <jiebin.sun@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Reviewed-by: Tianyou Li <tianyou.li@intel.com>
Reviewed-by: Wangyang Guo <wangyang.guo@intel.com>
---
 tools/perf/Documentation/perf-c2c.txt | 33 +++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/perf/Documentation/perf-c2c.txt b/tools/perf/Documentation/perf-c2c.txt
index e57a122b8719..43a3f195048a 100644
--- a/tools/perf/Documentation/perf-c2c.txt
+++ b/tools/perf/Documentation/perf-c2c.txt
@@ -365,6 +365,39 @@ TUI OUTPUT
 The TUI output provides interactive interface to navigate
 through cachelines list and to display offset details.
 
+Pressing the 'TAB' key in the cacheline view switches to the function
+view.  The function view shows a three-level hierarchy of the same data,
+organized around functions rather than cachelines:
+
+  Level 1: primary functions, sorted by Cycles % (estimated load cycles:
+           HITM, peer-snoop and other-load cycles -- on systems whose
+           default display mode is peer, such as Arm64, the peer-snoop
+           component dominates)
+  Level 2: other functions that share cachelines with the level-1 function
+  Level 3: the specific shared cachelines for each function pair
+
+In the function view the 'd' key opens the detail view of the selected
+cacheline, 'e'/'+' expands or collapses the current entry, and 'TAB',
+'ESC' or 'q' returns to the cacheline view.
+
+For example, expanding a level-1 function reveals the functions it shares
+cachelines with, and expanding one of those reveals the specific shared
+cachelines:
+
+  Shared Data Functions Table   (27 entries, sorted on Cycles %)
+   Cycles  Store
+        %  count  Code address        Symbol           Cacheline
+  ----------------------------------------------------------------------
+  - 39.03%   541  - 0xffffffffa2fc5b08  - [k] cpupri_set
+             450  - 0xffffffffa2fa28a5  - [k] pull_rt_task
+             450                                      0xff2d0082809da080
+
+Here cpupri_set is the most contended function (39.03% of the estimated
+load cycles); it shares data with pull_rt_task (450 stores into the shared
+data); and the contention is on the single cacheline 0xff2d0082809da080.
+This is the false-sharing chain that the cacheline view otherwise leaves
+to be reconstructed by hand.
+
 For details please refer to the help window by pressing '?' key.
 
 CREDITS
-- 
2.52.0